remove return

.clang-tidy

@@ -0,0 +1,27 @@
+Checks: >-
+  -*,
+  readability-identifier-naming,
+  readability-redundant-string-cstr,
+  readability-redundant-string-init,
+  readability-simplify-boolean-expr,
+  performance-unnecessary-value-param,
+  performance-unnecessary-copy-initialization,
+  performance-for-range-copy,
+  performance-implicit-conversion-in-loop,
+CheckOptions:
+- key:             readability-identifier-naming.PrivateMemberPrefix
+  value:           'm_'
+- key:             readability-identifier-naming.ClassConstantCase
+  value:           aNy_CasE
+# an empty *Prefix needs a *Case to work
+- key:             readability-identifier-naming.ClassConstantPrefix
+  value:           ''
+#- key:             readability-identifier-naming.PrivateMemberCase
+#  value:           CamelCase
+#- key:             readability-identifier-naming.FunctionCase
+#  value:           CamelCase
+#- key:             readability-identifier-naming.EnumCase
+#  value:           camelBack
+
+WarningsAsErrors: '*'
+FormatStyle: 'file'

.gitignore

@@ -9,3 +9,5 @@ build/
 .vscode
 
 imgui.ini
+
+test/tdmap.tdmap3

.vscode/c_cpp_properties.json

@@ -0,0 +1,13 @@
+{
+  "configurations": [
+    {
+      "name": "TD2",
+      "cppStandard": "c++20",
+      "includePath": [
+        "include"
+      ],
+      "compileCommands": ".vscode/compile_commands.json"
+    }
+  ],
+  "version": 4
+}

README.md

@@ -0,0 +1,3 @@
+# (CubeCraft) Tower Defense
+
+## Currently in contruction 🏗️👷⚙️

assets/stats.json

@@ -0,0 +1,5 @@
+{
+	"Zombie" : {
+		
+	}
+}

include/client/Client.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <client/IClientSocket.h>
+#include <client/PlayerManager.h>
+#include <td/common/StateMachine.h>
+#include <optional>
+
+namespace td {
+namespace client {
+
+class ClientState;
+class LoggingState;
+
+class Client : public StateMachine<Client, void, float> {
+  private:
+	std::shared_ptr<IClientSocket> m_Socket;
+	PlayerManager m_Players;
+	std::optional<PlayerID> m_Id;
+
+  public:
+	Client(const std::shared_ptr<IClientSocket>& a_Socket);
+	~Client();
+
+	void SendPacket(const protocol::PacketBase& a_Packet);
+
+	void Disconnect();
+
+	const PlayerManager& GetPlayers() const {
+		return m_Players;
+	}
+
+	const std::optional<PlayerID> GetId() const {
+		return m_Id;
+	}
+
+	friend class ClientState;
+	friend class LoggingState;
+};
+
+}  // namespace client
+}  // namespace td

include/client/ClientState.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <client/Client.h>
+#include <td/misc/SlotGuard.h>
+
+namespace td {
+namespace client {
+
+class ClientState : public Client::State, public protocol::PacketHandler, private utils::SlotGuard {
+  public:
+	ClientState(Client& a_Client);
+	virtual ~ClientState() {}
+
+  protected:
+	void SendPacket(const protocol::PacketBase& a_Packet);
+};
+
+}  // namespace server
+}  // namespace td

include/client/IClientSocket.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <td/Types.h>
+#include <td/misc/Signal.h>
+#include <td/protocol/packet/Packets.h>
+
+namespace td {
+namespace client {
+
+class IClientSocket {
+  public:
+	utils::Signal<> OnConnect;
+	utils::Signal<> OnDisconnect;
+	utils::Signal<const protocol::PacketBase&> OnReceive;
+
+	virtual void Send(const protocol::PacketBase& a_Packet) = 0;
+	virtual void Disconnect() = 0;
+
+	IClientSocket() {}
+	virtual ~IClientSocket() {}
+};
+
+}  // namespace client
+}  // namespace td

include/client/PlayerManager.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <td/protocol/packet/Packets.h>
+#include <td/misc/Signal.h>
+
+namespace td {
+namespace client {
+
+class IClientSocket;
+
+class PlayerManager : public protocol::PacketHandler {
+  private:
+	std::map<PlayerID, PlayerInfo> m_Players;
+	std::shared_ptr<IClientSocket> m_Socket;
+
+  public:
+	utils::Signal<const PlayerInfo&> OnPlayerJoin;
+	utils::Signal<PlayerID> OnPlayerLeave;
+
+	PlayerManager(const std::shared_ptr<IClientSocket>& a_Socket);
+	~PlayerManager();
+
+	PlayerInfo GetPlayer(PlayerID a_Player);
+
+	auto begin() const {
+		return m_Players.begin();
+	}
+
+	auto end() const {
+		return m_Players.end();
+	}
+
+	virtual void Handle(const protocol::packets::PlayerJoinPacket&) override;
+	virtual void Handle(const protocol::packets::PlayerListPacket&) override;
+	virtual void Handle(const protocol::packets::PlayerLeavePacket&) override;
+};
+
+}  // namespace client
+}  // namespace td

include/client/socket/FakeSocket.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <client/IClientSocket.h>
+
+namespace td {
+
+namespace server {
+class FakeSocket;
+}  // namespace server
+
+
+namespace client {
+
+class FakeSocket : public IClientSocket {
+  private:
+	std::shared_ptr<server::FakeSocket> m_Server;
+	PeerID m_PeerId;
+
+	struct Private{ explicit Private() = default; };
+
+  public:
+	FakeSocket(Private) {}
+	~FakeSocket() {}
+
+	static std::shared_ptr<FakeSocket> Connect(const std::shared_ptr<server::FakeSocket>& a_Server);
+
+	void ReceiveFromFakePeer(PeerID a_Peer, const protocol::PacketBase& a_Packet);
+
+	virtual void Send(const protocol::PacketBase& a_Packet) override;
+	virtual void Disconnect() override;
+};
+
+}  // namespace client
+}  // namespace td

include/client/state/GameState.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <client/ClientState.h>
+#include <td/game/World.h>
+#include <td/simulation/ClientSimulation.h>
+
+namespace td {
+namespace client {
+
+class GameState : public ClientState {
+  private:
+	game::WorldPtr m_World;
+	sim::ClientSimulation m_Simulation;
+	float m_CurrentLerp;
+
+  public:
+	GameState(Client& a_Client, const game::WorldPtr& a_World, std::uint64_t a_StepTime, const std::vector<protocol::LockStep> a_FirstSteps);
+	~GameState() {}
+
+	virtual void Update(float a_Delta) override;
+
+	float GetCurrentLerp() const {
+		return m_CurrentLerp;
+	}
+
+	game::WorldPtr GetWorld() const {
+		return m_World;
+	}
+
+	virtual void Handle(const protocol::packets::LockStepsPacket& a_LockStep) override;
+	virtual void Handle(const protocol::packets::LockStepResponsePacket& a_LockStep) override;
+};
+
+}  // namespace client
+}  // namespace td

include/client/state/LobbyState.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <client/ClientState.h>
+#include <td/game/World.h>
+#include <td/simulation/ClientSimulation.h>
+
+namespace td {
+namespace client {
+
+class LobbyState : public ClientState {
+  private:
+	std::shared_ptr<game::World> m_World;
+  public:
+	LobbyState(Client& a_Client);
+	~LobbyState();
+
+	virtual void Update(float a_Delta) override;
+
+	virtual void Handle(const protocol::packets::WorldHeaderPacket& a_Packet) override;
+	virtual void Handle(const protocol::packets::WorldDataPacket& a_Packet) override;
+	virtual void Handle(const protocol::packets::BeginGamePacket& a_Packet) override;
+};
+
+}  // namespace client
+}  // namespace td

include/client/state/LoggingState.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <client/ClientState.h>
+#include <td/game/World.h>
+#include <td/simulation/ClientSimulation.h>
+
+namespace td {
+namespace client {
+
+class LoggingState : public ClientState {
+  public:
+	LoggingState(Client& a_Client, const std::string& a_PlayerName);
+	~LoggingState();
+
+	virtual void Update(float a_Delta) override;
+
+	virtual void Handle(const protocol::packets::PlayerJoinPacket& a_Packet) override;
+	virtual void Handle(const protocol::packets::LoggingSuccessPacket& a_Packet) override;
+};
+
+}  // namespace client
+}  // namespace td

include/server/IServerSocket.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <server/PlayerIds.h>
+#include <td/misc/Signal.h>
+#include <td/protocol/packet/Packets.h>
+
+namespace td {
+namespace server {
+
+class IServerSocket {
+  public:
+	using PlayerPacketHandlerType = std::unique_ptr<protocol::PacketHandler>(PlayerID);
+	using PlayerPacketHandler = std::function<PlayerPacketHandlerType>;
+
+	utils::Signal<PlayerID> OnPlayerConnect;
+	utils::Signal<PlayerID> OnPlayerDisconnect;
+	utils::Signal<PlayerID, const protocol::PacketBase&> OnReceive;
+
+	void Send(PlayerID a_PlayerId, const protocol::PacketBase& a_Packet);
+	void Broadcast(const protocol::PacketBase& a_Packet);
+
+	void Disconnect(PlayerID a_PlayerId);
+
+	void RegisterHandler(const PlayerPacketHandler& a_Handler);
+	void UnregisterHandler(const PlayerPacketHandler& a_Handler);
+
+	IServerSocket();
+	virtual ~IServerSocket() {}
+
+  private:
+	PlayerIds m_Ids;
+	std::vector<PlayerPacketHandler> m_Handlers;
+
+  protected:
+	void OnConnectPeer(PeerID a_PeerId);
+	void OnDisconnectPeer(PeerID a_PeerId);
+	void OnReceivePeer(PeerID a_PeerId, const protocol::PacketBase& a_Packet);
+	virtual void SendPeer(PeerID a_PeerId, const protocol::PacketBase& a_Packet) = 0;
+};
+
+}  // namespace server
+}  // namespace td

include/server/PlayerIds.h

@@ -0,0 +1,49 @@
+#pragma once
+
+#include <map>
+#include <td/Types.h>
+
+namespace td {
+namespace server {
+
+class PlayerIds {
+  private:
+	std::map<PeerID, PlayerID> m_PeerToPlayer;
+	std::map<PlayerID, PeerID> m_PlayerToPeer;
+	PlayerID m_NextId;
+
+  public:
+	PlayerIds() : m_NextId(0) {}
+	~PlayerIds() {}
+
+	void AddConnection(PeerID a_PeerId) {
+		m_PeerToPlayer.emplace(a_PeerId, m_NextId);
+		m_PlayerToPeer.emplace(m_NextId, a_PeerId);
+		m_NextId++;
+	}
+
+	PlayerID GetPlayerId(PeerID a_PeerId) const {
+		return m_PeerToPlayer.at(a_PeerId);
+	}
+
+	PeerID GetPeerId(PlayerID a_PlayerId) const {
+		return m_PlayerToPeer.at(a_PlayerId);
+	}
+
+	void RemovePeer(PeerID a_PeerId) {
+		PlayerID playerId = GetPlayerId(a_PeerId);
+		m_PeerToPlayer.erase(a_PeerId);
+		m_PlayerToPeer.erase(playerId);
+	}
+
+	auto begin() {
+		return m_PeerToPlayer.begin();
+	}
+
+	auto end() {
+		return m_PeerToPlayer.end();
+	}
+};
+
+}  // namespace server
+}  // namespace td

include/server/PlayerManager.h

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <td/misc/Signal.h>
+#include <td/protocol/packet/Packets.h>
+
+namespace td {
+namespace server {
+
+class IServerSocket;
+
+class PlayerManager {
+  private:
+	std::map<PlayerID, PlayerInfo> m_Players;
+	std::shared_ptr<IServerSocket> m_Socket;
+
+  public:
+	utils::Signal<PlayerID, const PlayerInfo&> OnPlayerJoin;
+	utils::Signal<PlayerID> OnPlayerLeave;
+
+	PlayerManager(const std::shared_ptr<IServerSocket>& a_Socket);
+	~PlayerManager();
+
+	void RemovePlayer(PlayerID a_Player);
+	PlayerInfo GetPlayer(PlayerID a_Player);
+
+  private:
+	void Disconnect(PlayerID a_Player);
+	
+	class ConnectionHandler : public protocol::PacketHandler {
+	  private:
+		PlayerManager& m_PlayerManager;
+		PlayerID m_Player;
+
+	  public:
+		ConnectionHandler(PlayerManager& a_PlayerManager, PlayerID a_Player);
+		~ConnectionHandler() = default;
+
+		virtual void Handle(const protocol::packets::PlayerLoginPacket& a_Packet) override;
+		virtual void Handle(const protocol::packets::DisconnectPacket& a_Packet) override;
+	};
+};
+
+}  // namespace server
+}  // namespace td

include/server/Server.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <server/IServerSocket.h>
+#include <td/common/StateMachine.h>
+#include <server/PlayerManager.h>
+
+namespace td {
+namespace server {
+
+class ServerState;
+
+class Server : public StateMachine<Server, void, float> {
+  private:
+	std::shared_ptr<IServerSocket> m_Socket;
+	PlayerManager m_Players;
+	float m_LastMspt;
+
+  public:
+	Server(const std::shared_ptr<IServerSocket>& a_Socket);
+
+	virtual void Update(float a_Delta);
+
+	const PlayerManager& GetPlayers() const {
+		return m_Players;
+	}
+
+	friend class ServerState;
+};
+
+}  // namespace server
+}  // namespace td

include/server/ServerState.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <server/Server.h>
+#include <td/misc/SlotGuard.h>
+
+namespace td {
+namespace server {
+
+class ServerState : public Server::State, private utils::SlotGuard {
+  public:
+	virtual void HandlePacket(PlayerID a_Id, const protocol::PacketBase& a_Packet) = 0;
+	virtual void Update(float a_Delta) = 0;
+	virtual void OnPlayerJoin(PlayerID a_Id, const td::PlayerInfo& a_Info) {}
+	virtual void OnPlayerLeave(PlayerID a_Id) {}
+
+	ServerState(Server& a_Server);
+	virtual ~ServerState();
+
+  protected:
+	void SendPacket(PlayerID a_Id, const protocol::PacketBase& a_Packet);
+	void BroadcastPacket(const protocol::PacketBase& a_Packet);
+};
+
+}  // namespace server
+}  // namespace td

include/server/socket/FakeSocket.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <client/socket/FakeSocket.h>
+#include <optional>
+#include <server/IServerSocket.h>
+
+namespace td {
+namespace server {
+
+class FakeSocket : public IServerSocket {
+  private:
+	std::vector<std::optional<std::weak_ptr<client::FakeSocket>>> m_Clients;
+
+  public:
+	FakeSocket() {}
+	~FakeSocket() {}
+
+	PeerID ConnectFakePeer(const std::shared_ptr<client::FakeSocket>& a_Socket);
+	void DisconnectFakePeer(PeerID a_Peer);
+	void ReceiveFromFakePeer(PeerID a_Peer, const protocol::PacketBase& a_Packet);
+
+  protected:
+	virtual void SendPeer(PeerID a_Peer, const protocol::PacketBase& a_Packet) override;
+
+  private:
+	/**
+	 * \return -1 if all previous ids are not free
+	 */
+	int GetNextFreeId();
+
+	friend class client::FakeSocket;
+};
+
+}  // namespace server
+}  // namespace td

include/server/state/EndGameState.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <server/ServerState.h>
+
+namespace td {
+namespace server {
+
+class EndGameState : public ServerState {
+  private:
+	/* data */
+  public:
+	EndGameState(/* args */) {}
+	~EndGameState() {}
+};
+
+}  // namespace server
+}  // namespace td

include/server/state/GameState.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <server/ServerState.h>
+#include <td/game/World.h>
+#include <td/simulation/ServerSimulation.h>
+
+namespace td {
+namespace server {
+
+class GameStateHandler;
+
+class GameState : public ServerState {
+  private:
+	std::shared_ptr<game::World> m_World;
+	sim::ServerSimulation m_Simulation;
+	float m_Time;
+
+  public:
+	GameState(Server& a_Server, const std::shared_ptr<game::World>& a_World);
+	~GameState() {}
+
+	virtual void HandlePacket(PlayerID a_Id, const protocol::PacketBase& a_Packet) override;
+	virtual void Update(float a_Delta) override;
+
+	virtual void OnPlayerJoin(PlayerID a_Id, const td::PlayerInfo& a_Info) override;
+
+	friend class GameStateHandler;
+};
+
+}  // namespace server
+}  // namespace td

include/server/state/GameStateHandler.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <td/protocol/packet/Packets.h>
+
+namespace td {
+namespace server {
+
+class GameState;
+
+class GameStateHandler : public protocol::PacketHandler {
+  private:
+	GameState& m_GameState;
+	PlayerID m_PlayerId;
+
+	using protocol::PacketHandler::Handle;
+
+  public:
+	GameStateHandler(GameState& a_GameState, PlayerID a_PlayerId);
+
+	virtual void Handle(const protocol::packets::SpawnTroopPacket& a_Packet) override;
+	virtual void Handle(const protocol::packets::PlaceTowerPacket& a_Packet) override;
+	virtual void Handle(const protocol::packets::LockStepRequestPacket& a_Packet) override;
+};
+
+}  // namespace server
+}  // namespace td

include/server/state/LobbyState.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <server/ServerState.h>
+
+namespace td {
+namespace server {
+
+// this class is temporary useless
+class LobbyState : public ServerState {
+  private:
+	std::shared_ptr<game::World> m_World;
+  public:
+	LobbyState(Server& a_Server);
+	~LobbyState() {}
+
+	virtual void OnPlayerJoin(PlayerID a_Id, const td::PlayerInfo& a_Info) override;
+
+	virtual void HandlePacket(PlayerID a_Id, const protocol::PacketBase& a_Packet) override;
+	virtual void Update(float a_Delta) override;
+};
+
+}  // namespace server
+}  // namespace td

include/td/Constants.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <cstdint>
+
+namespace td {
+
+constexpr int TPS = 20;
+constexpr float STEP_PERIOD = 1.0f / static_cast<float>(TPS);
+
+}  // namespace td

include/td/Maths.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <cstdint>
+#include <sp/common/DataBufferOperators.h>
 
 namespace td {
 
@@ -18,7 +18,7 @@ struct Vec2 {
 		T g;
 	};
 
-	constexpr Vec2(T X = 0, T Y = 0) : x(X), y(Y) {}
+	constexpr Vec2(T X = T(0), T Y = T(0)) : x(X), y(Y) {}
 };
 
 template <typename T>
@@ -176,8 +176,42 @@ Mat4f Look(const Vec3f& eye, const Vec3f& center, const Vec3f& up);
 
 Mat4f Inverse(const Mat4f& mat);
 
+template<typename T>
+T Lerp(T v0, T v1, T t) {
+	return (T(1) - t) * v0 + t * v1;
+}
+
 }  // namespace maths
 
+template <typename T>
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const Vec2<T>& a_Vec) {
+	return a_Buffer << a_Vec.x << a_Vec.y;
+}
 
+template <typename T>
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, Vec2<T>& a_Vec) {
+	return a_Buffer >> a_Vec.x >> a_Vec.y;
+}
+
+template <typename T>
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const Vec3<T>& a_Vec) {
+	return a_Buffer << a_Vec.x << a_Vec.y << a_Vec.z;
+}
+
+template <typename T>
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, Vec3<T>& a_Vec) {
+	return a_Buffer >> a_Vec.x >> a_Vec.y >> a_Vec.z;
+}
+
+
+template <typename T>
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const Vec4<T>& a_Vec) {
+	return a_Buffer << a_Vec.x << a_Vec.y << a_Vec.z << a_Vec.w;
+}
+
+template <typename T>
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, Vec4<T>& a_Vec) {
+	return a_Buffer >> a_Vec.x >> a_Vec.y >> a_Vec.z >> a_Vec.w;
+}
 
 }  // namespace td

include/td/Types.h

@@ -2,11 +2,20 @@
 
 #include <cstdint>
 #include <fpm/fixed.hpp>
+#include <td/Maths.h>
+
+namespace sp {
+class DataBuffer;
+} // namespace sp
 
 namespace td {
 
 using FpFloat = fpm::fixed_16_16;
 
+using StepTime = std::uint16_t;
+
+constexpr int STEP_TIME = 50;
+
 enum class TeamColor : std::int8_t {
 	None = -1,
 	Blue,
@@ -31,7 +40,7 @@ enum class EntityType : std::uint8_t {
 	Zombie = 0,
 	Spider,
 	Pigman,
-	Skeleton,
+	Skelon,
 	Creeper,
 	Silverfish,
 	Blaze,
@@ -56,15 +65,9 @@ using TowerID = std::uint16_t;
 using PlayerID = std::uint8_t;
 using EntityID = std::uint16_t;
 
-struct TowerCoords {
-	std::int16_t x;
-	std::int16_t y;
-};
+using TowerCoords = Vec2<std::int16_t>;
 
-struct EntityCoords {
-	FpFloat x;
-	FpFloat y;
-};
+using EntityCoords = Vec2<FpFloat>;
 
 using PeerID = std::uint16_t;
 
@@ -75,4 +78,15 @@ enum class Direction : std::uint8_t {
 	NegativeY = 1 << 3,
 };
 
+struct PlayerInfo {
+	PlayerID m_PlayerId;
+	std::string m_PlayerName;
+};
+
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const EntityCoords& a_Coords);
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const FpFloat& a_Float);
+
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, EntityCoords& a_Coords);
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, FpFloat& a_Float);
+
 }  // namespace td

include/td/common/Array.h

@@ -48,6 +48,10 @@ class Array {
 		return m_Data[a_Index];
 	}
 
+	const T& operator[](std::size_t a_Index) const {
+		return m_Data[a_Index];
+	}
+
 	~Array() {
 		delete [] m_Data;
 	}

include/td/common/StateMachine.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include <cassert>
+#include <td/misc/Signal.h>
+
+namespace td {
+
+template <typename TDerived, typename TReturn, typename... TArgs>
+class StateMachine {
+  public:
+	class State {
+	  public:
+		State(TDerived& a_StateMachine) : m_StateMachine(a_StateMachine) {}
+		virtual ~State() {}
+
+		virtual TReturn Update(TArgs... args) = 0;
+
+		template <typename T, typename... Args>
+		void ChangeState(Args... args) {
+			m_StateMachine.template ChangeState<T>(std::forward<Args>(args)...);
+		}
+
+	  protected:
+		TDerived& m_StateMachine;
+	};
+
+	utils::Signal<State&> OnStateChange;
+
+	StateMachine() {}
+	StateMachine(StateMachine&&) = default;
+	virtual ~StateMachine() {}
+
+	virtual TReturn Update(TArgs... args) {
+		assert(m_State && "You must change state at least once before updating !");
+		return m_State->Update(std::forward<TArgs>(args)...);
+	}
+
+	template <typename T, typename... Args>
+	void ChangeState(Args... args) {
+		auto* currentState = m_State.get();
+		auto newState = std::make_unique<T>(static_cast<TDerived&>(*this), std::forward<Args>(args)...);
+		// This allows chaining
+		if (m_State.get() == currentState) {
+			m_State = std::move(newState);
+			OnStateChange(*m_State);
+		}
+	}
+
+  private:
+	std::unique_ptr<State> m_State;
+};
+
+
+}  // namespace td

include/td/common/StateStack.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#include <cassert>
+#include <vector>
+#include <memory>
+
+namespace td {
+
+template <typename TDerived, typename TReturn, typename... TArgs>
+class StateStack {
+  public:
+	class State {
+	  public:
+		State(TDerived& a_StateStack) : m_StateStack(a_StateStack) {}
+		virtual ~State() {}
+
+		virtual TReturn Update(TArgs... args) = 0;
+
+	  protected:
+		/**
+		 * \brief Called when enabled (can be used to connect signals)
+		 */
+		virtual void OnEnable() {}
+
+		/**
+		 * \brief Called when disabled (can be used to disconnect signals)
+		 */
+		virtual void OnDisable() {}
+
+	  protected:
+		TDerived& m_StateStack;
+
+		friend class StateStack;
+	};
+
+	StateStack() {}
+	StateStack(StateStack&&) = default;
+	virtual ~StateStack() {}
+
+	virtual TReturn Update(TArgs... args) {
+		assert(!m_States.empty() && "You must push at least one state before updating !");
+		return m_States.back()->Update(args...);
+	}
+
+	void PopState() {
+		assert(!m_States.empty() && "You must push at least one state before poping !");
+		m_States.back()->OnDisable();
+		m_States.pop_back();
+		if (m_States.empty())
+			return;
+		m_States.back()->OnEnable();
+	}
+
+	template <typename T, typename... Args>
+	T* PushState(Args&&... args) {
+		if (!m_States.empty())
+			m_States.back()->OnDisable();
+		auto newState = std::make_unique<T>(static_cast<TDerived&>(*this), std::forward<Args>(args)...);
+		newState->OnEnable();
+		m_States.push_back(std::move(newState));
+		return static_cast<T*>(newState.get());
+	}
+
+  private:
+	std::vector<std::unique_ptr<State>> m_States;
+};
+
+
+}  // namespace td

include/td/display/Display.h

@@ -2,17 +2,33 @@
 
 #include <string>
 
+#include <SDL3/SDL_keycode.h>
 #include <SDL3/SDL_video.h>
+#include <td/common/StateMachine.h>
+#include <td/misc/Signal.h>
 
 namespace td {
 
-class Display {
+class Display : public StateMachine<Display, void, float> {
+  private:
+	SDL_Window* m_Window;
+	SDL_GLContext m_GLContext;
+
+	int m_LastWidth, m_LastHeight;
+	float m_AspectRatio;
+
+	bool m_ShouldClose;
+
   public:
+	utils::Signal<float> OnAspectRatioChange;
+	utils::Signal<SDL_Keycode> OnKeyDown;
+
 	Display(int a_Width, int a_Height, const std::string& a_Title);
 	~Display();
 
 	void PollEvents();
-	void Update();
+	void Update(float a_Delta) override;
+	void Close();
 
 	bool IsCloseRequested() {
 		return m_ShouldClose;
@@ -29,15 +45,6 @@ class Display {
 	int GetWindowHeight() {
 		return m_LastHeight;
 	}
-
-  private:
-	SDL_Window* m_Window;
-	SDL_GLContext m_GLContext;
-
-	int m_LastWidth, m_LastHeight;
-	float m_AspectRatio;
-
-	bool m_ShouldClose;
 };
 
 }  // namespace td

include/td/display/DisplayState.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <td/display/Display.h>
+#include <td/misc/SlotGuard.h>
+#include <client/ClientState.h>
+
+namespace td {
+
+class DisplayState : public Display::State, private utils::SlotGuard {
+  public:
+	DisplayState(Display& a_Display);
+	virtual ~DisplayState() {}
+
+  protected:
+	virtual void OnAspectRatioChange(float a_Ratio) {}
+	virtual void OnKeyDown(SDL_Keycode a_Key) {}
+};
+
+}  // namespace td

include/td/display/ImGuiTheme.h

@@ -0,0 +1,7 @@
+#pragma once
+
+namespace td {
+
+void LoadTheme();
+
+}  // namespace td

include/td/display/menu/CreatePartyMenu.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <td/display/state/MainMenuState.h>
+
+namespace td {
+
+class CreatePartyMenu : public MainMenuState::Menu {
+  public:
+	CreatePartyMenu(MainMenuState& a_MainMenu);
+	~CreatePartyMenu();
+
+	virtual void Update() override;
+};
+
+}  // namespace td

include/td/display/menu/JoinPartyMenu.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <td/display/state/MainMenuState.h>
+
+namespace td {
+
+class JoinPartyMenu : public MainMenuState::Menu {
+  public:
+	JoinPartyMenu(MainMenuState& a_MainMenu);
+	~JoinPartyMenu();
+
+	virtual void Update() override;
+};
+
+}  // namespace td

include/td/display/menu/MainMenu.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <td/display/state/MainMenuState.h>
+
+namespace td {
+
+class MainMenu : public MainMenuState::Menu {
+  public:
+	MainMenu(MainMenuState& a_MainMenu);
+	~MainMenu();
+
+	virtual void Update() override;
+};
+
+}  // namespace td

include/td/display/menu/SettingsMenu.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <td/display/state/MainMenuState.h>
+
+namespace td {
+
+class SettingsMenu : public MainMenuState::Menu {
+  public:
+	SettingsMenu(MainMenuState& a_MainMenu);
+	~SettingsMenu();
+
+	virtual void Update() override;
+};
+
+}  // namespace td

include/td/display/state/DebugWorldState.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <client/Client.h>
+#include <server/Server.h>
+#include <td/display/DisplayState.h>
+#include <td/render/Renderer.h>
+#include <td/simulation/ClientSimulation.h>
+#include <client/state/GameState.h>
+#include <server/socket/FakeSocket.h>
+
+namespace td {
+
+class DebugWorldState : public DisplayState {
+  private:
+	render::RenderPipeline m_Renderer;
+	render::Camera m_Camera;
+	std::unique_ptr<server::Server> m_Server;
+	std::unique_ptr<client::Client> m_Client;
+	client::GameState* m_ClientState;
+
+	std::vector<std::unique_ptr<client::Client>> m_FakeClients;
+	std::shared_ptr<server::FakeSocket> m_ServerSocket;
+
+  public:
+	DebugWorldState(Display& a_Display);
+	~DebugWorldState();
+
+	virtual void Update(float a_Delta) override;
+
+  protected:
+	virtual void OnAspectRatioChange(float a_Ratio) override;
+	virtual void OnKeyDown(SDL_Keycode a_Key) override;
+};
+
+}  // namespace td

include/td/display/state/MainMenuState.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <td/common/StateStack.h>
+#include <td/display/DisplayState.h>
+
+namespace td {
+
+class MainMenuState;
+
+using MainMenuStateStack = StateStack<MainMenuState, void>;
+
+class MainMenuState : public DisplayState, public MainMenuStateStack {
+  public:
+	using Menu = MainMenuStateStack::State;
+
+	MainMenuState(Display& a_Display);
+	~MainMenuState();
+
+	virtual void Update(float a_Delta) override;
+
+	void RenderBackButton();
+
+  protected:
+	virtual void OnKeyDown(SDL_Keycode a_Key) override;
+};
+
+}  // namespace td

include/td/game/GameHistory.h

@@ -1,37 +0,0 @@
-#pragma once
-
-#include <optional>
-#include <td/protocol/command/Commands.h>
-#include <td/protocol/packet/Packets.h>
-
-namespace td {
-namespace game {
-
-class GameHistory {
-  private:
-	using HistorySizeType = std::uint16_t;
-
-	std::vector<std::optional<protocol::LockStep>> m_History;
-	
-	HistorySizeType m_Cursor;
-
-  public:
-	GameHistory();
-
-	void SetLockStep(HistorySizeType a_Index, protocol::LockStep&& a_LockStep);
-
-	const protocol::LockStep& GetLockStep(HistorySizeType a_Index) const;
-
-	bool HasLockStep(HistorySizeType a_Index) const;
-
-	const protocol::LockStep& GetNextStep();
-
-	bool HasNextStep() const;
-
-	void FromPacket(td::protocol::pdata::LockSteps&& a_Steps);
-
-	td::protocol::packets::LockStepsPacket ToPacket(HistorySizeType a_StartIndex);
-};
-
-}  // namespace game
-}  // namespace td

include/td/game/Mobs.h

@@ -9,10 +9,14 @@
 #include <memory>
 #include <vector>
 
-namespace td {
-namespace game {
+#include <sp/protocol/ConcreteMessage.h>
+#include <sp/common/GenericHandler.h>
+#include <sp/protocol/MessageFactory.h>
 
-struct WalkableTile;
+namespace td {
+using Vec2fp = Vec2<FpFloat>;
+
+namespace game {
 
 enum class EffectType : std::uint8_t {
 	Slowness = 0,
@@ -62,151 +66,33 @@ const MobStats* GetMobStats(MobType type, std::uint8_t level);
 const TowerImmunities& GetMobTowerImmunities(MobType type, std::uint8_t level);
 const EffectImmunities& GetMobEffectImmunities(MobType type, std::uint8_t level);
 
-class Mob : public utils::shape::Rectangle {
-  protected:
-	float m_Health;
+class MobHandler;
 
-  private:
+struct MobData {};
+
+class Mob : public sp::MessageBase<MobType, MobHandler> {
+  public:
 	MobID m_ID;
-	PlayerID m_Sender;
 	MobLevel m_Level;
+	PlayerID m_Sender;
+	float m_Health;
+	Vec2fp m_Position;
 	Direction m_Direction;
 	std::vector<EffectDuration> m_Effects;
 	const Tower* m_LastDamage;	// the last tower that damaged the mob
 	float m_HitCooldown;
-
-	// utils::Timer m_EffectFireTimer;
-	// utils::Timer m_EffectPoisonTimer;
-	// utils::Timer m_EffectHealTimer;
-
 	TeamCastle* m_CastleTarget;
 	// utils::CooldownTimer m_AttackTimer;
 
-  public:
-	Mob(MobID id, MobLevel level, PlayerID sender) : m_Sender(sender), m_Level(level), m_HitCooldown(0), m_CastleTarget(nullptr) {}
+	MobPtr m_Next;
 
-	virtual ~Mob() {}
+	Mob() {}
 
-	virtual MobType GetType() const = 0;
-
-	virtual void Tick(std::uint64_t delta, World* world) {}
-
-	virtual bool OnDeath(World* world) {
-		return true;
-	}
-
-	MobID GetMobID() const {
-		return m_ID;
-	}
-	const TowerImmunities& GetTowerImmunities() const {
-		return GetMobTowerImmunities(GetType(), m_Level);
-	}
-	const EffectImmunities& GetEffectImmunities() const {
-		return GetMobEffectImmunities(GetType(), m_Level);
-	}
-	PlayerID GetSender() const {
-		return m_Sender;
-	}
-	MobLevel GetLevel() const {
-		return m_Level;
-	}
-	const MobStats* GetStats() const {
-		return GetMobStats(GetType(), m_Level);
-	}
-	void SetHealth(float newHealth) {
-		m_Health = newHealth;
-	}
-	float GetHealth() const {
-		return m_Health;
-	}
-	bool IsDead() const {
-		return m_Health <= 0;
-	}
-	bool IsAlive() const {
-		return m_Health > 0;
-	}
-	const Tower* GetLastDamageTower() {
-		return m_LastDamage;
-	}
-	bool HasReachedEnemyCastle() {
-		return m_CastleTarget != nullptr;
-	}
-
-	void Damage(float dmg, const Tower* damager) {
-		m_Health = std::max(0.0f, m_Health - dmg);
-		m_LastDamage = damager;
-		m_HitCooldown = 0.1;
-	}
-
-	void Heal(float heal) {
-		m_Health = std::min(static_cast<float>(GetStats()->m_MaxLife), m_Health + heal);
-	}
-
-	void SetMobReachedCastle(TeamCastle* castle) {
-		m_CastleTarget = castle;
-	}  // used when mob is in front of the castle
-
-	bool IsImmuneTo(TowerType type);
-
-	bool IsImmuneTo(EffectType type);
-	void AddEffect(EffectType type, float durationSec, Tower* tower);
-	bool HasEffect(EffectType type);
-
-	bool HasTakenDamage() {
-		return m_HitCooldown > 0;
-	}
-
-	// returns a float between 0 and 1 excluded
-	float GetTileX() {
-		return GetCenterX() - static_cast<float>(static_cast<std::int32_t>(GetCenterX()));
-	}
-
-	// returns a float between 0 and 1 excluded
-	float GetTileY() {
-		return GetCenterY() - static_cast<float>(static_cast<std::int32_t>(GetCenterY()));
-	}
-
-	Direction GetDirection() const {
-		return m_Direction;
-	}
-	void SetDirection(Direction dir) {
-		m_Direction = dir;
-	}
-
-  protected:
-	void InitMob() {
-		m_Health = static_cast<float>(GetStats()->m_MaxLife);
-		SetSize(GetStats()->m_Size.x, GetStats()->m_Size.y);
-	}
-
-  private:
-	void UpdateEffects(std::uint64_t delta, World* world);
-	void AttackCastle(std::uint64_t delta, World* world);
-	void Move(std::uint64_t delta, World* world);
-	void Walk(std::uint64_t delta, World* world);
-	void MoveBack(const TeamCastle& castle, World* world);
-	void ChangeDirection(const WalkableTile& tile, World* world);
-	bool IsTouchingCastle(const TeamCastle& castle) const;
-	EffectDuration& GetEffect(EffectType type);
+	Mob& operator=(const Mob& a_Other) = default;
 };
 
-typedef std::shared_ptr<Mob> MobPtr;
-
-template <MobType MT>
-class ConcreteMob : public Mob {
-  public:
-	ConcreteMob(MobID id, std::uint8_t level, PlayerID sender) : Mob(id, level, sender) {
-		InitMob();
-	}
-
-	virtual ~ConcreteMob() {}
-
-	virtual void Tick(std::uint64_t delta, World* world) {}
-
-	virtual constexpr MobType GetType() const {
-		return MT;
-	}
-};
+template <MobType ID>
+using ConcreteMob = sp::ConcreteMessage<MobData, Mob, ID>;
 
 using Zombie = ConcreteMob<MobType::Zombie>;
 using Spider = ConcreteMob<MobType::Spider>;
@@ -219,16 +105,17 @@ using Witch = ConcreteMob<MobType::Witch>;
 using Slime = ConcreteMob<MobType::Slime>;
 using Giant = ConcreteMob<MobType::Giant>;
 
-namespace MobFactory {
+using AllMobs = std::tuple<Zombie, Spider, Skeleton, PigMan, Creeper, Silverfish, Blaze, Witch, Slime, Giant>;
 
-MobPtr CreateMob(MobID id, MobType type, std::uint8_t level, PlayerID sender);
-std::string GetMobName(MobType type);
+class MobHandler : public sp::GenericHandler<AllMobs> {};
 
-}  // namespace MobFactory
+using MobFactory = sp::MessageFactory<Mob, AllMobs>;
 
 class MobListener {
   public:
-	virtual void OnMobSpawn(Mob* mob) {}
+	virtual void OnMobSpawn(Mob* mob) {
+		MobHandler h;
+	}
 	virtual void OnMobDie(Mob* mob) {}
 
 	virtual void OnMobDamage(Mob* target, float damage, Tower* damager) {}
@@ -237,6 +124,8 @@ class MobListener {
 	virtual void OnMobCastleDamage(Mob* damager, TeamCastle* enemyCastle, float damage) {}
 };
 
+using MobList = std::vector<MobPtr>;
+
 // typedef utils::ObjectNotifier<MobListener> MobNotifier;
 
 }  // namespace game

include/td/game/Team.h

@@ -17,7 +17,7 @@ class Spawn : public utils::shape::Rectangle {
 private:
 	Direction m_Direction;
 public:
-	Spawn() {
+	Spawn() : m_Direction(Direction::PositiveX) {
 		SetWidth(5);
 		SetHeight(5);
 	}
@@ -31,23 +31,17 @@ class Team;
 
 class TeamCastle : public utils::shape::Rectangle {
 private:
-	const Team* m_Team;
 	float m_Life;
 public:
 	static constexpr int CastleMaxLife = 1000;
 
-	TeamCastle(const Team* team) : m_Team(team), m_Life(CastleMaxLife) {
+	TeamCastle() : m_Life(CastleMaxLife) {
 		SetWidth(5);
 		SetHeight(5);
 	}
 
-	TeamCastle() : TeamCastle(nullptr) {}
-
 	float GetLife() const { return m_Life; }
 
-	const Team* GetTeam() const { return m_Team; }
-	void SetTeam(const Team* team) { m_Team = team; }
-
 	void SetLife(float life) { m_Life = life; }
 	void Damage(float damage) { m_Life = std::max(0.0f, m_Life - damage); }
 
@@ -80,7 +74,29 @@ public:
 	std::uint8_t GetPlayerCount() const;
 };
 
-typedef std::array<Team, 2> TeamList;
+struct TeamList {
+	std::array<Team, 2> m_Teams;
+
+	TeamList() : m_Teams{Team{TeamColor::Blue}, Team{TeamColor::Red}}{
+		
+	}
+
+	Team& operator[](std::size_t a_Index) {
+		return m_Teams[a_Index];
+	}
+
+	Team& operator[](TeamColor a_Index) {
+		return m_Teams[static_cast<std::size_t>(a_Index)];
+	}
+
+	const Team& operator[](std::size_t a_Index) const {
+		return m_Teams[a_Index];
+	}
+
+	const Team& operator[](TeamColor a_Index) const {
+		return m_Teams[static_cast<std::size_t>(a_Index)];
+	}
+};
 
 } // namespace game
 } // namespace td

include/td/game/Towers.h

@@ -1,12 +1,16 @@
 #pragma once
 
-#include <string>
 #include <memory>
+#include <string>
 
 #include <td/misc/Shapes.h>
 
 #include <td/Types.h>
 
+#include <sp/common/GenericHandler.h>
+#include <sp/protocol/ConcreteMessage.h>
+#include <sp/protocol/MessageFactory.h>
+
 namespace td {
 namespace game {
 
@@ -15,23 +19,6 @@ class Mob;
 
 typedef std::shared_ptr<Mob> MobPtr;
 
-enum class TowerType : std::uint8_t {
-	Archer = 0,
-	Ice,
-	Sorcerer,
-	Zeus,
-	Mage,
-	Artillery,
-	Quake,
-	Poison,
-
-	Leach,
-	Turret,
-	Necromancer,
-
-	TowerCount
-};
-
 enum class TowerSize : std::uint8_t {
 	Little = 3,	 // 3x3
 	Big = 5,	 // 5x5
@@ -48,14 +35,19 @@ private:
 	float m_Rate;
 	float m_Damage;
 	std::uint8_t m_Range;
-public:
-	TowerStats(float rate, float damage, std::uint8_t range) : m_Rate(rate), m_Damage(damage),
-		m_Range(range) {
-	}
 
-	float GetDamageRate() const { return m_Rate; }
-	float GetDamage() const { return m_Damage; }
-	std::uint8_t GetRange() const { return m_Range; }
+  public:
+	TowerStats(float rate, float damage, std::uint8_t range) : m_Rate(rate), m_Damage(damage), m_Range(range) {}
+
+	float GetDamageRate() const {
+		return m_Rate;
+	}
+	float GetDamage() const {
+		return m_Damage;
+	}
+	std::uint8_t GetRange() const {
+		return m_Range;
+	}
 };
 
 class TowerLevel {
@@ -64,15 +56,24 @@ private:
 	std::uint8_t m_Level : 3;
 	// 0 : base path       1 : top path (if there is bottom path)     2 : bottom path (if there is top path)
 	TowerPath m_Path : 2;
+
   public:
 	TowerLevel() : m_Level(1), m_Path(TowerPath::Base) {}
 	TowerLevel(std::uint8_t level, TowerPath path) : m_Level(level), m_Path(path) {}
 
-	std::uint8_t GetLevel() const { return m_Level; }
-	TowerPath GetPath() const { return m_Path; }
+	std::uint8_t GetLevel() const {
+		return m_Level;
+	}
+	TowerPath GetPath() const {
+		return m_Path;
+	}
 
-	void SetLevel(std::uint8_t level) { m_Level = level; }
-	void SetPath(TowerPath path) { m_Path = path; }
+	void SetLevel(std::uint8_t level) {
+		m_Level = level;
+	}
+	void SetPath(TowerPath path) {
+		m_Path = path;
+	}
 
 	// operator to sort maps
 	friend bool operator<(const TowerLevel& level, const TowerLevel& other) {
@@ -81,186 +82,66 @@ public:
 	}
 };
 
-const TowerStats* GetTowerStats(TowerType type, TowerLevel level);
+using TowerID = std::uint16_t;
 
-typedef std::uint16_t TowerID;
+class TowerHandler;
 
-class Tower : public utils::shape::Circle {
-private:
+class Tower : public utils::shape::Circle, public sp::MessageBase<TowerType, TowerHandler> {
+  public:
 	TowerID m_ID;
-	TowerType m_Type;
 	TowerLevel m_Level{};
 	PlayerID m_Builder;
-protected:
-	// utils::CooldownTimer m_Timer;
+
   public:
-	Tower(TowerID id, TowerType type, std::int32_t x, std::int32_t y, PlayerID builder) : utils::shape::Circle(x + 0.5f, y + 0.5f, 0), m_ID(id), m_Type(type), m_Builder(builder)
-		// m_Timer(GetStats()->GetDamageRate() * 1000) 
-		{ // converting seconds to millis
-		SetRadius(GetStats()->GetRange());
-	}
+	Tower() : m_ID(0), m_Level({}), m_Builder(0) {}
 
 	virtual TowerType GetType() const = 0;
 	virtual TowerSize GetSize() const = 0;
 	virtual void Tick(std::uint64_t delta, World* world) = 0;
+};
 
-	void Upgrade(std::uint8_t level, TowerPath path) {
-		m_Level.SetLevel(level);
-		m_Level.SetPath(path);
-		// m_Timer.SetCooldown(GetStats()->GetDamageRate() * 1000); // converting seconds to millis
-		// m_Timer.Reset();
-		SetRadius(GetStats()->GetRange());
+struct TowerData {};
+
+template <TowerType Type, TowerSize Size>
+class ConcreteTower : public sp::ConcreteMessage<TowerData, Tower, Type, false> {
+  public:
+	using HandlerType = typename sp::ConcreteMessage<TowerData, Tower, Type, false>::HandlerType;
+
+	virtual TowerSize GetSize() const override {
+		return Size;
 	}
 
-	std::uint16_t GetID() const { return m_ID; }
-	const TowerLevel& GetLevel() const { return m_Level; }
-	const TowerStats* GetStats() const { return GetTowerStats(m_Type, m_Level); }
-	PlayerID GetBuilder() const { return m_Builder; }
-
-	bool IsMobInRange(MobPtr mob);
-};
-
-typedef std::shared_ptr<Tower> TowerPtr;
-
-namespace TowerFactory {
-
-TowerPtr CreateTower(TowerType type, TowerID id, std::int32_t x, std::int32_t y, PlayerID builder);
-std::string GetTowerName(TowerType type);
-
-} // namespace TowerFactory
-
-
-class TowerInfo {
-private:
-	std::string m_Name, m_Description;
-	bool m_IsBigTower;
-public:
-	TowerInfo(std::string&& name, std::string&& description, bool big) : m_Name(std::move(name)),
-		m_Description(std::move(description)), m_IsBigTower(big) {
+	virtual TowerType GetType() const override {
+		return Type;
 	}
 
-	const std::string& GetName() const { return m_Name; }
-	const std::string& GetDescription() const { return m_Description; }
+	virtual void Tick(std::uint64_t delta, World* world) override {}
 
-	bool IsBigTower() const { return m_IsBigTower; }
+	virtual void Dispatch(HandlerType& handler) const override {
+		handler.Handle(*this);
+	}
 };
 
-const TowerInfo& GetTowerInfo(TowerType type);
+using TowerPtr = std::shared_ptr<Tower>;
 
-// ---------- Little Towers ----------
+using ArcherTower = ConcreteTower<TowerType::Archer, TowerSize::Little>;
+using ArtilleryTower = ConcreteTower<TowerType::Artillery, TowerSize::Little>;
+using IceTower = ConcreteTower<TowerType::Ice, TowerSize::Little>;
+using LeachTower = ConcreteTower<TowerType::Leach, TowerSize::Big>;
+using MageTower = ConcreteTower<TowerType::Mage, TowerSize::Little>;
+using NecromancerTower = ConcreteTower<TowerType::Necromancer, TowerSize::Big>;
+using PoisonTower = ConcreteTower<TowerType::Poison, TowerSize::Little>;
+using QuakeTower = ConcreteTower<TowerType::Quake, TowerSize::Little>;
+using SorcererTower = ConcreteTower<TowerType::Sorcerer, TowerSize::Little>;
+using TurretTower = ConcreteTower<TowerType::Turret, TowerSize::Big>;
+using ZeusTower = ConcreteTower<TowerType::Zeus, TowerSize::Little>;
 
-class LittleTower : public Tower {
-public:
-	LittleTower(TowerID id, TowerType type, std::uint16_t x, std::uint16_t y, PlayerID builder) : Tower(id, type, x, y, builder) {}
+using AllTowers = std::tuple<ArcherTower, ArtilleryTower, IceTower, LeachTower, MageTower, NecromancerTower, PoisonTower, QuakeTower,
+	SorcererTower, TurretTower, ZeusTower>;
 
-	virtual TowerSize GetSize() const { return TowerSize::Little; }
+using TowerFactory = sp::MessageFactory<Tower, AllTowers>;
 
-	virtual TowerType GetType() const = 0;
-	virtual void Tick(std::uint64_t delta, World* world) = 0;
-};
-
-class ArcherTower : public LittleTower {
-public:
-	ArcherTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : LittleTower(id, GetType(), x, y, builder) {}
-
-	constexpr static float ExplosionRadius = 1.5f;
-	constexpr static float FireDurationSec = 10.0f;
-
-	virtual TowerType GetType() const { return TowerType::Archer; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class IceTower : public LittleTower {
-public:
-	IceTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : LittleTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Ice; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class MageTower : public LittleTower {
-public:
-	MageTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : LittleTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Mage; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class PoisonTower : public LittleTower {
-public:
-	PoisonTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : LittleTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Poison; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class QuakeTower : public LittleTower {
-public:
-	QuakeTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : LittleTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Quake; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class ArtilleryTower : public LittleTower {
-public:
-	ArtilleryTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : LittleTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Artillery; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class SorcererTower : public LittleTower {
-public:
-	SorcererTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : LittleTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Sorcerer; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class ZeusTower : public LittleTower {
-public:
-	ZeusTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : LittleTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Zeus; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-// ---------- Big Towers ----------
-
-class BigTower : public Tower {
-public:
-	BigTower(TowerID id, TowerType type, std::uint16_t x, std::uint16_t y, PlayerID builder) : Tower(id, type, x, y, builder) {}
-
-	virtual TowerSize GetSize() const { return TowerSize::Big; }
-
-	virtual TowerType GetType() const = 0;
-	virtual void Tick(std::uint64_t delta, World* world) = 0;
-};
-
-class TurretTower : public BigTower {
-public:
-	TurretTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : BigTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Turret; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class NecromancerTower : public BigTower {
-public:
-	NecromancerTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : BigTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Necromancer; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
-
-class LeachTower : public BigTower {
-public:
-	LeachTower(TowerID id, std::uint16_t x, std::uint16_t y, PlayerID builder) : BigTower(id, GetType(), x, y, builder) {}
-
-	virtual TowerType GetType() const { return TowerType::Leach; }
-	virtual void Tick(std::uint64_t delta, World* world);
-};
+class TowerHandler : public sp::GenericHandler<AllTowers> {};
 
 }  // namespace game
 }  // namespace td

include/td/game/World.h

@@ -2,40 +2,43 @@
 
 #include <td/game/WorldTypes.h>
 #include <td/protocol/packet/Packets.h>
+#include <td/simulation/WorldTicker.h>
 
 namespace td {
 namespace game {
 
 class World {
   protected:
+	// header
 	TowerTileColorPalette m_TowerPlacePalette;
 	Color m_WalkablePalette;
 	std::vector<Color> m_DecorationPalette;
 	Color m_Background;
-
-	std::unordered_map<ChunkCoord, ChunkPtr> m_Chunks;
-
 	SpawnColorPalette m_SpawnColorPalette;
-
 	TilePalette m_TilePalette;
 
-	MobList m_Mobs;
+	//data
+	ChunkList m_Chunks;
 
-	TowerList m_Towers;
+	std::shared_ptr<sim::WorldSnapshot> m_CurrentState;
+	std::shared_ptr<sim::WorldSnapshot> m_NextState;
 
-	TeamList m_Teams;
+  private:
+	sim::WorldTicker m_Ticker;
 
   public:
 	World();
+	World(World&&) = default;
 
 	bool LoadMap(const protocol::pdata::WorldHeader& worldHeader);
 	bool LoadMap(const protocol::pdata::WorldData& worldData);
 
+	protocol::packets::WorldHeaderPacket GetPacketHeader() const;
+	protocol::packets::WorldDataPacket GetPacketData() const;
+
 	bool LoadMapFromFile(const std::string& fileName);
 	bool SaveMap(const std::string& fileName) const;
 
-	void Tick(std::uint64_t delta);
-
 	void SpawnMobAt(MobID id, MobType type, std::uint8_t level, PlayerID sender, float x, float y, Direction dir);
 
 	TowerPtr PlaceTowerAt(TowerID id, TowerType type, std::int32_t x, std::int32_t y, PlayerID builder);
@@ -62,7 +65,7 @@ class World {
 
 	TilePtr GetTilePtr(TileIndex index) const {
 		if (index == 0)
-			return nullptr;
+			return TilePtr(nullptr);
 		return m_TilePalette.at(index - 1);
 	}
 
@@ -71,7 +74,7 @@ class World {
 
 	TowerPtr GetTower(const Vec2f& position) const;	 // returns null if no tower is here
 
-	const std::unordered_map<ChunkCoord, ChunkPtr>& GetChunks() const {
+	const ChunkList& GetChunks() const {
 		return m_Chunks;
 	}
 
@@ -83,55 +86,57 @@ class World {
 	}
 
 	const MobList& GetMobList() const {
-		return m_Mobs;
+		return m_CurrentState->m_Mobs;
 	}
 	MobList& GetMobList() {
-		return m_Mobs;
+		return m_CurrentState->m_Mobs;
 	}
 
-	const Color* GetTileColor(TilePtr tile) const;
+	const Color* GetTileColor(const TilePtr& tile) const;
 
 	Team& GetRedTeam() {
-		return m_Teams[static_cast<std::uint8_t>(TeamColor::Red)];
+		return m_CurrentState->m_Teams[TeamColor::Red];
 	}
 	const Team& GetRedTeam() const {
-		return m_Teams[static_cast<std::uint8_t>(TeamColor::Red)];
+		return m_CurrentState->m_Teams[TeamColor::Red];
 	}
 
 	Team& GetBlueTeam() {
-		return m_Teams[static_cast<std::uint8_t>(TeamColor::Blue)];
+		return m_CurrentState->m_Teams[TeamColor::Blue];
 	}
 	const Team& GetBlueTeam() const {
-		return m_Teams[static_cast<std::uint8_t>(TeamColor::Red)];
+		return m_CurrentState->m_Teams[TeamColor::Blue];
 	}
 
 	Team& GetTeam(TeamColor team) {
-		return m_Teams[static_cast<std::uint8_t>(team)];
+		return m_CurrentState->m_Teams[team];
 	}
 	const Team& GetTeam(TeamColor team) const {
-		return m_Teams[static_cast<std::uint8_t>(team)];
+		return m_CurrentState->m_Teams[team];
 	}
 
 	const TeamList& GetTeams() const {
-		return m_Teams;
+		return m_CurrentState->m_Teams;
 	}
 
 	const TowerList& GetTowers() const {
-		return m_Towers;
+		return m_CurrentState->m_Towers;
 	}
 
 	TowerPtr GetTowerById(TowerID tower);
 
 	const Player* GetPlayerById(PlayerID id) const;
 
+	const std::shared_ptr<sim::WorldSnapshot>& Tick(const protocol::LockStep& a_LockStep, FpFloat a_Delta);
+
+	void ResetSnapshots(std::shared_ptr<sim::WorldSnapshot>& a_Current, std::shared_ptr<sim::WorldSnapshot>& a_Next);
+
   private:
 	void TickMobs(std::uint64_t delta);
 	void CleanDeadMobs();
 };
 
-
-
-
+using WorldPtr = std::shared_ptr<World>;
 
 }  // namespace game
 }  // namespace td

include/td/game/WorldTypes.h

@@ -1,20 +1,15 @@
 #pragma once
 
 #include <td/Maths.h>
-#include <td/game/Mobs.h>
 #include <td/game/Team.h>
 #include <td/game/Towers.h>
 
+#include <sp/io/SerializableMessage.h>
+
 namespace td {
 namespace game {
-struct ChunkCoord {
-	std::int16_t x, y;
-
-	friend bool operator==(const td::game::ChunkCoord& first, const td::game::ChunkCoord& other) {
-		return first.x == other.x && first.y == other.y;
-	}
-};
 
+using ChunkCoord = Vec2<std::int16_t>;
 
 class Game;
 
@@ -37,36 +32,44 @@ static constexpr Color RED{255, 0, 0};
 static constexpr Color GREEN{0, 255, 0};
 static constexpr Color BLUE{0, 0, 255};
 
-struct Tile {
-	virtual TileType GetType() const = 0;
+class TileHandler;
+
+using Tile = sp::MessageBase<TileType, TileHandler>;
+
+template <TileType ID, typename TileData>
+using ConcreteTile = sp::ConcreteMessage<TileData, Tile, ID>;
+
+namespace data {
+struct EmptyData {};
+
+struct TowerTileData {
+	std::uint8_t m_ColorPaletteRef;
+	TeamColor m_TeamOwner;
 };
 
-struct TowerTile : Tile {
-	std::uint8_t color_palette_ref;
-	TeamColor team_owner;
-
-	virtual TileType GetType() const {
-		return TileType::Tower;
-	}
+struct WalkableTileData {
+	Direction m_Direction;
 };
 
-struct WalkableTile : Tile {
-	Direction direction;
-
-	virtual TileType GetType() const {
-		return TileType::Walk;
-	}
+struct DecorationTileData {
+	std::uint16_t m_ColorPaletteRef;
 };
+}  // namespace data
 
-struct DecorationTile : Tile {
-	std::uint16_t color_palette_ref;
+using EmptyTile = ConcreteTile<TileType::None, data::EmptyData>;
+using TowerTile = ConcreteTile<TileType::Tower, data::TowerTileData>;
+using WalkableTile = ConcreteTile<TileType::Walk, data::WalkableTileData>;
+using DecorationTile = ConcreteTile<TileType::Decoration, data::DecorationTileData>;
 
-	virtual TileType GetType() const {
-		return TileType::Decoration;
-	}
-};
+using AllTiles = std::tuple<EmptyTile, TowerTile, WalkableTile, DecorationTile>;
 
-typedef std::shared_ptr<Tile> TilePtr;
+using TileFactory = sp::MessageFactory<Tile, AllTiles>;
+
+class TileHandler : public sp::GenericHandler<AllTiles> {};
+
+using TilePtr = sp::SerializableMessage<TileFactory>;
+
+// typedef std::shared_ptr<Tile> TilePtr;
 typedef std::vector<std::uint16_t> ChunkPalette;
 
 typedef std::shared_ptr<WalkableTile> WalkableTilePtr;
@@ -76,18 +79,14 @@ typedef std::uint32_t TileIndex;
 // 32 x 32 area
 struct Chunk {
 	enum { ChunkWidth = 32, ChunkHeight = 32, ChunkSize = ChunkWidth * ChunkHeight };
-	typedef std::array<std::uint16_t, ChunkSize> ChunkData;
+	using ChunkData = std::array<std::uint16_t, ChunkSize>;
+	using ChunkPackedData = std::vector<uint64_t>;
 
 	// stores index of tile palette
-	ChunkData tiles{0};
-	ChunkPalette palette;
+	ChunkPalette m_Palette;
+	ChunkPackedData m_Data;
 
-	TileIndex GetTileIndex(std::uint16_t tileNumber) const {
-		TileIndex chunkPaletteIndex = tiles.at(tileNumber);
-		if (chunkPaletteIndex == 0)	 // index 0 means empty tile     index 1 = first tile
-			return 0;
-		return palette.at(chunkPaletteIndex);
-	}
+	TileIndex GetTileIndex(std::uint16_t tileNumber) const;
 };
 
 typedef std::shared_ptr<Chunk> ChunkPtr;
@@ -96,12 +95,11 @@ typedef std::array<Color, 2> TowerTileColorPalette;
 
 typedef std::vector<TilePtr> TilePalette;
 
-typedef std::vector<MobPtr> MobList;
-
 typedef std::array<Color, 2> SpawnColorPalette;
 
 typedef std::vector<TowerPtr> TowerList;
 
+using ChunkList = std::unordered_map<ChunkCoord, ChunkPtr>;
 
 }  // namespace game
 

include/td/misc/Shapes.h

@@ -30,7 +30,7 @@ private:
 	Point m_Center;
 	float m_Width, m_Height;
 public:
-	Rectangle() {}
+	Rectangle() : m_Center(), m_Width(0), m_Height(0) {}
 
 	const Point& GetCenter() const { return m_Center; }
 	float GetCenterX() const { return m_Center.GetX(); }

include/td/misc/Signal.h

@@ -2,30 +2,104 @@
 
 #include <algorithm>
 #include <functional>
+#include <memory>
 #include <td/common/NonCopyable.h>
 #include <vector>
 
 namespace td {
 namespace utils {
 
+/**
+ * \brief Signal class
+ */
 template <typename... Args>
-class Signal : private NonCopyable {
-  private:
-	using CallBack = std::function<void(Args...)>;
+class SignalRaw : private NonCopyable {
+  public:
+	using FnType = void(Args...);
+	using CallBack = std::shared_ptr<std::function<FnType>>;
 
+  private:
 	std::vector<CallBack> m_Callbacks;
 
   public:
-	void Connect(CallBack&& a_Callback) {
-		m_Callbacks.push_back(std::move(a_Callback));
+	void Connect(const CallBack& a_Callback) {
+		m_Callbacks.push_back(a_Callback);
+	}
+
+	void Disconnect(const CallBack& a_Callback) {
+		auto it = std::find(m_Callbacks.begin(), m_Callbacks.end(), a_Callback);
+		m_Callbacks.erase(it);
 	}
 
 	void operator()(Args... args) const {
 		for (const CallBack& callback : m_Callbacks) {
-			callback(args...);
+			callback->operator()(args...);
 		}
 	}
 };
 
+/**
+ * \brief Memory managed Signal class
+ */
+template <typename... Args>
+class Signal {
+  public:
+	using SignalBase = SignalRaw<Args...>;
+	using CallBack = typename SignalBase::CallBack;
+	using CallBackRaw = typename CallBack::element_type;
+	using SignalPtr = std::shared_ptr<SignalBase>;
+	class ConnectionGuard;
+
+  private:
+	SignalPtr m_Signal;
+
+  public:
+	Signal() : m_Signal(std::make_shared<SignalBase>()) {}
+	Signal(const Signal&) = default;
+
+	/**
+	 * \warning The callback won't be disconnectable, use it wisely!
+	 */
+	void Connect(const CallBackRaw& a_Callback) {
+		m_Signal->Connect(std::make_shared<CallBackRaw>(a_Callback));
+	}
+
+	[[nodiscard]] std::unique_ptr<ConnectionGuard> ConnectSafe(const CallBack& a_Callback) {
+		m_Signal->Connect(a_Callback);
+		return std::make_unique<ConnectionGuard>(*this, a_Callback);
+	}
+
+	void Disconnect(const CallBack& a_Callback) {
+		m_Signal->Disconnect(a_Callback);
+	}
+
+	void operator()(Args... args) const {
+		m_Signal->operator()(args...);
+	}
+};
+
+class Connection {
+  public:
+	virtual ~Connection() {}
+};
+
+template <typename... Args>
+class Signal<Args...>::ConnectionGuard : public Connection {
+  private:
+	using CallBack = typename Signal<Args...>::CallBack;
+
+	std::weak_ptr<SignalRaw<Args...>> m_Signal;
+	CallBack m_Callback;
+
+  public:
+	ConnectionGuard(const Signal<Args...>& a_Signal, const CallBack& a_Callback) :
+		m_Signal(a_Signal.m_Signal), m_Callback(a_Callback) {}
+
+	~ConnectionGuard() {
+		if (!m_Signal.expired())
+			m_Signal.lock()->Disconnect(m_Callback);
+	}
+};
+
 }  // namespace utils
 }  // namespace td

include/td/misc/SlotGuard.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <td/misc/Signal.h>
+
+namespace td {
+namespace utils {
+
+/**
+ * \brief Wrapper class to automatically disconnect from a Signal on object destruction
+ * \note You should inherit this class privately
+ * \sa Signal
+ */
+class SlotGuard {
+  private:
+	std::vector<std::unique_ptr<Connection>> m_Connections;
+
+  public:
+	/**
+	 * \brief Connect a signal to a function (with the same signature)
+	 */
+	template <typename... Args>
+	void Connect(Signal<Args...> a_Signal, const typename Signal<Args...>::CallBack::element_type& a_Callback) {
+		auto ptr = std::make_shared<typename Signal<Args...>::CallBack::element_type>(a_Callback);
+		m_Connections.push_back(a_Signal.ConnectSafe(ptr));
+	}
+
+	void Disconnect() {
+		m_Connections.clear();
+	}
+};
+
+}  // namespace utils
+}  // namespace td

include/td/misc/Time.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <chrono>
+
+namespace td {
+
+class Timer {
+  private:
+	std::chrono::time_point<std::chrono::system_clock> m_LastTime;
+
+  public:
+	Timer() : m_LastTime(std::chrono::system_clock::now()) {}
+
+	float GetDelta() {
+		auto timeElapsed = std::chrono::system_clock::now() - m_LastTime;
+		float timeSeconds = std::chrono::duration<float, std::chrono::seconds::period>(timeElapsed).count();
+		m_LastTime = std::chrono::system_clock::now();
+		return timeSeconds;
+	}
+};
+
+}  // namespace td

include/td/network/EnetClient.h

@@ -0,0 +1 @@
+#pragma once

include/td/network/EnetConnection.h

@@ -0,0 +1 @@
+#pragma once

include/td/network/EnetServer.h

@@ -0,0 +1 @@
+#pragma once

include/td/protocol/Dispatcher.h

@@ -1,61 +0,0 @@
-#pragma once
-
-/**
- * \file PacketDispatcher.h
- * \brief File containing the td::protocol::PacketDispatcher class
- */
-
-#include <td/common/NonCopyable.h>
-#include <td/protocol/packet/Packets.h>
-
-#include <map>
-
-namespace td {
-namespace protocol {
-
-/**
- * \class Dispatcher
- * \brief Class used to dispatch things
- */
-template <typename T_Enum, typename T_Handler, typename T>
-class Dispatcher : private NonCopyable {
-  private:
-	std::map<T_Enum, std::vector<T_Handler*>> m_Handlers;
-
-  public:
-	/**
-	 * \brief Constructor
-	 */
-	Dispatcher() {}
-
-	/**
-	 * \brief Dispatch a packet
-	 * \param packet The packet to dispatch
-	 */
-	void Dispatch(const T& packet);
-
-	/**
-	 * \brief Register a packet handler
-	 * \param type The packet type
-	 * \param handler The packet handler
-	 */
-	void RegisterHandler(T_Enum type, T_Handler& handler);
-
-	/**
-	 * \brief Unregister a packet handler
-	 * \param type The packet type
-	 * \param handler The packet handler
-	 */
-	void UnregisterHandler(T_Enum type, T_Handler& handler);
-
-	/**
-	 * \brief Unregister a packet handler
-	 * \param handler The packet handler
-	 */
-	void UnregisterHandler(T_Handler& handler);
-};
-
-}  // namespace protocol
-}  // namespace td
-
-#include "Dispatcher.inl"

include/td/protocol/Dispatcher.inl

@@ -1,38 +0,0 @@
-#pragma once
-
-namespace td {
-namespace protocol {
-
-template <typename T_Enum, typename T_Handler, typename T>
-void Dispatcher<T_Enum, T_Handler, T>::Dispatch(const T& packet) {
-	T_Enum type = packet.GetType();
-	for (auto* handler : m_Handlers[type])
-		handler->Check(packet);
-}
-
-template <typename T_Enum, typename T_Handler, typename T>
-void Dispatcher<T_Enum, T_Handler, T>::RegisterHandler(T_Enum type, T_Handler& handler) {
-	auto found = std::find(m_Handlers[type].begin(), m_Handlers[type].end(), &handler);
-	if (found == m_Handlers[type].end())
-		m_Handlers[type].push_back(&handler);
-}
-
-template <typename T_Enum, typename T_Handler, typename T>
-void Dispatcher<T_Enum, T_Handler, T>::UnregisterHandler(T_Enum type, T_Handler& handler) {
-	m_Handlers[type].erase(std::remove(m_Handlers[type].begin(), m_Handlers[type].end(), &handler), m_Handlers[type].end());
-}
-
-template <typename T_Enum, typename T_Handler, typename T>
-void Dispatcher<T_Enum, T_Handler, T>::UnregisterHandler(T_Handler& handler) {
-	for (auto& pair : m_Handlers) {
-		if (pair.second.empty())
-			continue;
-
-		PacketType type = pair.first;
-
-		m_Handlers[type].erase(std::remove(m_Handlers[type].begin(), m_Handlers[type].end(), &handler), m_Handlers[type].end());
-	}
-}
-
-}  // namespace protocol
-}  // namespace td

include/td/protocol/command/Commands.h

@@ -6,14 +6,16 @@
  */
 
 #include <memory>
+#include <sp/common/GenericHandler.h>
 #include <sp/protocol/ConcreteMessage.h>
 #include <sp/protocol/MessageDispatcher.h>
 #include <sp/protocol/MessageFactory.h>
-#include <sp/protocol/MessageHandler.h>
 #include <td/Types.h>
 #include <td/common/NonCopyable.h>
 #include <td/protocol/command/CommandData.h>
 
+#include <sp/io/SerializableMessage.h>
+
 namespace td {
 namespace protocol {
 
@@ -33,7 +35,7 @@ class CommandHandler;
 using CommandBase = sp::MessageBase<CommandID, CommandHandler>;
 
 template <typename TData, CommandID ID>
-using CommandMessage = sp::ConcreteMessage<TData, CommandID, ID, CommandHandler>;
+using CommandMessage = sp::ConcreteMessage<TData, CommandBase, ID>;
 
 
 namespace commands {
@@ -51,13 +53,15 @@ using UseItemCommand = CommandMessage<cdata::UseItem, CommandID::UseItem>;
 using AllCommands = std::tuple<commands::EndCommand, commands::PlaceTowerCommand, commands::PlayerJoinCommand,
 	commands::SpawnTroopCommand, commands::TeamChangeCommand, commands::UpgradeTowerCommand, commands::UseItemCommand>;
 
-class CommandHandler : public sp::MessageHandler<AllCommands> {};
+class CommandHandler : public sp::GenericHandler<AllCommands> {};
 
 using CommandDispatcher = sp::MessageDispatcher<CommandBase>;
 
 using CommandFactory = sp::MessageFactory<CommandBase, AllCommands>;
 
-using LockStep = std::vector<std::shared_ptr<CommandBase>>;
+using CommandPtr = sp::SerializableMessage<CommandFactory>;
+
+using LockStep = std::vector<CommandPtr>;
 
 }  // namespace protocol
 }  // namespace td

include/td/protocol/packet/PacketData.h

@@ -7,32 +7,31 @@
 #include <td/game/WorldTypes.h>
 
 // Make it dynamic ?
+#ifdef NDEBUG
 #define LOCKSTEP_BUFFER_SIZE 10
+#else
+#define LOCKSTEP_BUFFER_SIZE 1
+#endif
 
 namespace td {
 namespace protocol {
 
-struct PlayerInfo {
-	PlayerID m_PlayerId;
-	std::string m_PlayerName;
-};
-
 struct MapData {
 
 };
 
 namespace pdata {
 
-/** Client attempts to login (very basic) */
-struct PlayerLogin {
-	std::string m_PlayerName;
-};
-
 /** Server indicates success */
 struct LoggingSuccess {
 	PlayerID m_PlayerId;
 };
 
+/** Client attempts to login (very basic) */
+struct PlayerLogin {
+	std::string m_PlayerName;
+};
+
 /** Player joins the lobby */
 struct PlayerJoin {
 	PlayerInfo m_Player;
@@ -43,6 +42,16 @@ struct PlayerLeave {
 	PlayerID m_PlayerId;
 };
 
+/** List of players who joined before */
+struct PlayerList {
+	std::vector<PlayerInfo> m_Players;
+};
+
+struct PredictCommand {
+	CommandPtr m_Command;
+	StepTime m_FrameNumber;
+};
+
 /** Keep alive */
 struct KeepAlive {
 	std::uint64_t m_KeepAliveId;
@@ -58,8 +67,6 @@ struct ChatMessage {
 	std::string m_Text;
 };
 
-// TODO: handle players joining in the first second
-
 struct BeginGame {
 	std::vector<PlayerInfo> m_BlueTeam;
 	std::vector<PlayerInfo> m_RedTeam;
@@ -68,8 +75,8 @@ struct BeginGame {
 };
 
 struct LockSteps {
-	std::uint16_t m_FirstFrameNumber;
-	Array<LockStep, LOCKSTEP_BUFFER_SIZE> m_LockSteps;
+	StepTime m_FirstFrameNumber;
+	std::array<LockStep, LOCKSTEP_BUFFER_SIZE> m_LockSteps;
 };
 
 struct WorldHeader {
@@ -87,7 +94,26 @@ struct WorldHeader {
 };
 
 struct WorldData {
-	std::unordered_map<game::ChunkCoord, game::ChunkPtr> m_Chunks;
+	game::ChunkList m_Chunks;
+};
+
+// TODO: spawn multiple troops at the same time
+struct SpawnTroop {
+	sp::BitField<EntityType, 5> m_Type;
+	sp::BitField<std::uint8_t, 3> m_Level;
+};
+
+struct PlaceTower {
+	TowerType m_Type;
+	TowerCoords m_Position;
+};
+
+struct LockStepRequest {
+	std::vector<StepTime> m_Missing;
+};
+
+struct LockStepResponse {
+	std::map<StepTime, LockStep> m_Steps;
 };
 
 }  // namespace pdata

include/td/protocol/packet/PacketSerialize.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <td/protocol/packet/PacketData.h>
+
+namespace td {
+
+
+
+namespace game {
+
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const TeamCastle& a_Castle);
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, TeamCastle& a_Castle);
+
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const Spawn& a_Spawn);
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, Spawn& a_Spawn);
+
+}  // namespace game
+}  // namespace td

include/td/protocol/packet/Packets.h

@@ -8,11 +8,11 @@
 #include <td/common/NonCopyable.h>
 #include <td/protocol/packet/PacketData.h>
 
+#include <sp/common/GenericHandler.h>
 #include <sp/protocol/ConcreteMessage.h>
 #include <sp/protocol/MessageBase.h>
 #include <sp/protocol/MessageDispatcher.h>
 #include <sp/protocol/MessageFactory.h>
-#include <sp/protocol/MessageHandler.h>
 
 namespace td {
 namespace protocol {
@@ -22,11 +22,17 @@ enum class PacketID : std::uint8_t {
 	BeginGame,
 	Disconnect,
 	KeepAlive,
+	LockStepRequest,
+	LockStepResponse,
 	LockSteps,
 	LoggingSuccess,
+	PlaceTower,
 	PlayerJoin,
 	PlayerLeave,
+	PlayerList,
 	PlayerLogin,
+	PredictCommand,
+	SpawnTroop,
 	WorldHeader,
 	WorldData,
 };
@@ -37,7 +43,7 @@ using PacketBase = sp::MessageBase<PacketID, PacketHandler>;
 
 
 template <typename TData, PacketID ID>
-using PacketMessage = sp::ConcreteMessage<TData, PacketID, ID, PacketHandler>;
+using PacketMessage = sp::ConcreteMessage<TData, PacketBase, ID>;
 
 
 namespace packets {
@@ -46,22 +52,34 @@ using BeginGamePacket = PacketMessage<pdata::BeginGame, PacketID::BeginGame>;
 using ChatMessagePacket = PacketMessage<pdata::ChatMessage, PacketID::ChatMessage>;
 using DisconnectPacket = PacketMessage<pdata::Disconnect, PacketID::Disconnect>;
 using KeepAlivePacket = PacketMessage<pdata::KeepAlive, PacketID::KeepAlive>;
+using LockStepRequestPacket = PacketMessage<pdata::LockStepRequest, PacketID::LockStepRequest>;
+using LockStepResponsePacket = PacketMessage<pdata::LockStepResponse, PacketID::LockStepResponse>;
 using LockStepsPacket = PacketMessage<pdata::LockSteps, PacketID::LockSteps>;
 using LoggingSuccessPacket = PacketMessage<pdata::LoggingSuccess, PacketID::LoggingSuccess>;
+using PlaceTowerPacket = PacketMessage<pdata::PlaceTower, PacketID::PlaceTower>;
 using PlayerJoinPacket = PacketMessage<pdata::PlayerJoin, PacketID::PlayerJoin>;
 using PlayerLeavePacket = PacketMessage<pdata::PlayerLeave, PacketID::PlayerLeave>;
+using PlayerListPacket = PacketMessage<pdata::PlayerList, PacketID::PlayerList>;
 using PlayerLoginPacket = PacketMessage<pdata::PlayerLogin, PacketID::PlayerLogin>;
+using PredictCommandPacket = PacketMessage<pdata::PredictCommand, PacketID::PredictCommand>;
+using SpawnTroopPacket = PacketMessage<pdata::SpawnTroop, PacketID::SpawnTroop>;
 using WorldHeaderPacket = PacketMessage<pdata::WorldHeader, PacketID::WorldHeader>;
 using WorldDataPacket = PacketMessage<pdata::WorldData, PacketID::WorldData>;
 
-
 }  // namespace packets
 
 using AllPackets = std::tuple<packets::BeginGamePacket, packets::ChatMessagePacket, packets::DisconnectPacket,
-	packets::KeepAlivePacket, packets::LockStepsPacket, packets::LoggingSuccessPacket, packets::PlayerJoinPacket,
-	packets::PlayerLeavePacket, packets::PlayerLoginPacket, packets::WorldHeaderPacket, packets::WorldDataPacket>;
+	packets::KeepAlivePacket, packets::LockStepRequestPacket, packets::LockStepResponsePacket, packets::LockStepsPacket,
+	packets::LoggingSuccessPacket, packets::PlaceTowerPacket, packets::PlayerJoinPacket, packets::PlayerLeavePacket,
+	packets::PlayerListPacket, packets::PlayerLoginPacket, packets::PredictCommandPacket, packets::SpawnTroopPacket,
+	packets::WorldHeaderPacket, packets::WorldDataPacket>;
 
-class PacketHandler : public sp::MessageHandler<AllPackets> {};
+class PacketHandler : public sp::GenericHandler<AllPackets> {
+  public:
+	void HandleBase(const PacketBase& a_Packet) {
+		a_Packet.Dispatch(*this);
+	}
+};
 
 using PacketDispatcher = sp::MessageDispatcher<PacketBase>;
 

include/td/render/Renderer.h

@@ -4,19 +4,21 @@
 #include <td/render/Camera.h>
 #include <td/render/loader/GLLoader.h>
 #include <td/render/shader/CameraShaderProgram.h>
+#include <td/misc/SlotGuard.h>
 
 namespace td {
 namespace render {
 
 class BasicRenderer {
   public:
-	virtual void Render() = 0;
+	virtual void Render(float a_Lerp) = 0;
+	virtual ~BasicRenderer() {}
 
 	void Render(const GL::VertexArray& a_Vao);
 };
 
 template <typename TShader>
-class Renderer : public BasicRenderer {
+class Renderer : public BasicRenderer, private utils::SlotGuard {
   protected:
 	std::unique_ptr<TShader> m_Shader;
 	Camera& m_Camera;
@@ -24,6 +26,11 @@ class Renderer : public BasicRenderer {
   public:
 	Renderer(Camera& a_Camera);
 	virtual ~Renderer() {}
+
+	template <typename T>
+	float Lerp(const T& a_Mob, float a_LerpFactor, const std::function<float(const T&)>& a_MemberGetter) {
+		return static_cast<float>(maths::Lerp(a_MemberGetter(a_Mob), a_MemberGetter(*a_Mob.m_Next), a_LerpFactor));
+	}
 };
 
 class RenderPipeline {
@@ -32,20 +39,23 @@ class RenderPipeline {
 
   public:
 	RenderPipeline();
-	~RenderPipeline() = default;
+	virtual ~RenderPipeline() {}
 
 	template <typename T, typename... Args>
-	void AddRenderer(Args&&... args) {
-		m_Renderers.push_back(std::make_unique<T>(args...));
+	T& AddRenderer(Args&&... args) {
+		auto ptr = std::make_unique<T>(args...);
+		auto rawPtr = ptr.get();
+		m_Renderers.push_back(std::move(ptr));
+		return *rawPtr;
 	}
 
 	void Clear() {
 		m_Renderers.clear();
 	}
 
-	void Render() {
+	void Render(float a_Lerp) {
 		for (auto& renderer : m_Renderers) {
-			renderer->Render();
+			renderer->Render(a_Lerp);
 		}
 	}
 };
@@ -56,12 +66,12 @@ class RenderPipeline {
 
 template <typename TShader>
 Renderer<TShader>::Renderer(Camera& a_Camera) : m_Shader(std::make_unique<TShader>()), m_Camera(a_Camera) {
-	a_Camera.OnPerspectiveChange.Connect([this]() {
+	Connect(a_Camera.OnPerspectiveChange, [this](){
 		m_Shader->Start();
 		m_Shader->SetProjectionMatrix(m_Camera.GetProjectionMatrix());
 	});
 
-	a_Camera.OnViewChange.Connect([this]() {
+	Connect(a_Camera.OnViewChange, [this]() {
 		m_Shader->Start();
 		m_Shader->SetViewMatrix(m_Camera.GetViewMatrix());
 	});

include/td/render/loader/WorldLoader.h

@@ -16,7 +16,7 @@ struct RenderData {
 GL::VertexArray LoadMobModel();
 GL::VertexArray LoadWorldModel(const td::game::World* world);
 GL::VertexArray LoadTileSelectModel();
-RenderData LoadTowerModel(game::TowerPtr tower);
+RenderData LoadTowerModel(const game::TowerPtr& tower);
 
 } // namespace WorldLoader
 

include/td/render/renderer/EntityRenderer.h

@@ -9,14 +9,14 @@ namespace render {
 
 class EntityRenderer : public Renderer<shader::EntityShader> {
   private:
-	const game::World& m_World;
+	game::WorldPtr m_World;
 	std::unique_ptr<GL::VertexArray> m_EntityVao;
 
   public:
-	EntityRenderer(Camera& a_Camera, const game::World& a_World);
+	EntityRenderer(Camera& a_Camera, const game::WorldPtr& a_World);
 	virtual ~EntityRenderer();
 
-	virtual void Render() override;
+	virtual void Render(float a_Lerp) override;
 };
 
 }  // namespace render

include/td/render/renderer/PlayerListRenderer.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <td/render/Renderer.h>
+#include <client/PlayerManager.h>
+
+namespace td {
+namespace render {
+
+/**
+ * \brief This is a debug class
+ */
+class PlayerListRenderer : public BasicRenderer {
+  private:
+	const client::PlayerManager& m_Players;
+  public:
+	utils::Signal<> OnPlayerCreate;
+	// utils::Signal<> OnRequestPOV;
+	utils::Signal<PlayerID> OnPlayerKick;
+
+	virtual void Render(float a_Lerp) override;
+
+	PlayerListRenderer(const client::PlayerManager& a_Players);
+	~PlayerListRenderer() {}
+};
+
+}  // namespace render
+}  // namespace td

include/td/render/renderer/TowerRenderer.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <td/render/Renderer.h>
+#include <td/render/shader/EntityShader.h>
+#include <td/game/World.h>
+
+namespace td {
+namespace render {
+
+class TowerRenderer : public Renderer<shader::EntityShader> {
+  private:
+	game::WorldPtr m_World;
+	std::unique_ptr<GL::VertexArray> m_EntityVao;
+
+  public:
+	TowerRenderer(Camera& a_Camera, const game::WorldPtr& a_World);
+	virtual ~TowerRenderer();
+
+	virtual void Render(float a_Lerp) override;
+};
+
+}  // namespace render
+}  // namespace td

include/td/render/renderer/WorldRenderer.h

@@ -10,14 +10,13 @@ namespace render {
 
 class WorldRenderer : public Renderer<shader::WorldShader> {
   private:
-	const game::World& m_World;
 	std::unique_ptr<GL::VertexArray> m_WorldVao;
 
   public:
-	WorldRenderer(Camera& a_Camera, const game::World& a_World);
+	WorldRenderer(Camera& a_Camera, const game::WorldPtr& a_World);
 	virtual ~WorldRenderer();
 
-	virtual void Render() override;
+	virtual void Render(float a_Lerp) override;
 };
 
 }  // namespace render

include/td/simulation/ClientSimulation.h

@@ -0,0 +1,70 @@
+#pragma once
+
+#include <td/game/World.h>
+#include <optional>
+#include <td/misc/Signal.h>
+
+namespace td {
+namespace sim {
+
+using GameHistory = std::vector<td::protocol::LockStep>;
+using GameBuffer = std::vector<std::optional<td::protocol::LockStep>>;
+
+// TODO: OnEnd signal
+class ClientSimulation : public protocol::PacketHandler {
+  private:
+	std::uint64_t m_StepTime;
+	std::shared_ptr<game::World> m_World;
+	GameBuffer m_History;
+	float m_CurrentTime;
+	StepTime m_CurrentStep;
+
+	std::shared_ptr<WorldSnapshot> m_LastSnapshot;
+	StepTime m_LastValidStep;
+
+	static const protocol::LockStep EMPTY_LOCKSTEP;
+
+	using protocol::PacketHandler::Handle;
+
+  public:
+	utils::Signal<const std::vector<StepTime>&> OnMissingLockSteps;
+
+	/**
+	 * \brief Replay constructor
+	 * \param a_StepTime in ms
+	 */
+	ClientSimulation(std::shared_ptr<game::World> a_World, GameHistory&& a_History, std::uint64_t a_StepTime);
+
+	/**
+	 * \brief Live update constructor (continuous game updates)
+	 * \param a_StepTime in ms
+	 */
+	ClientSimulation(std::shared_ptr<game::World> a_World, std::uint64_t a_StepTime, const std::vector<protocol::LockStep>& a_FirstSteps);
+
+	/**
+	 * \return the progress [0-1] between two steps
+	 */
+	float Update(float a_Delta);
+
+	virtual void Handle(const protocol::packets::LockStepsPacket& a_LockSteps) override;
+	virtual void Handle(const protocol::packets::LockStepResponsePacket& a_LockSteps) override;
+
+  private:
+	/**
+	 * \returns false if the empty lockstep was used
+	 */
+	bool Step();
+
+	/**
+	 * \brief Ticks a_Count times
+	 */
+	std::size_t FastForward(std::size_t a_Count);
+
+	/**
+	 * \brief Tries to recompute simulation if needed (for example in late command receival)
+	 */
+	void FastReplay();
+};
+
+}  // namespace sim
+}  // namespace td

include/td/simulation/CommandApply.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <td/game/World.h>
+#include <td/protocol/command/Commands.h>
+
+namespace td {
+namespace sim {
+
+class CommandApply : public protocol::CommandHandler {
+  private:
+	const game::World& m_World;
+	WorldSnapshot& m_Snapshot;
+
+  public:
+	CommandApply(const game::World& a_World, WorldSnapshot& a_Snapshot);
+
+	virtual void Handle(const protocol::commands::EndCommand& a_End) override;
+	virtual void Handle(const protocol::commands::PlaceTowerCommand& a_PlaceTower) override;
+	virtual void Handle(const protocol::commands::PlayerJoinCommand& a_PlayerJoin) override;
+	virtual void Handle(const protocol::commands::SpawnTroopCommand& a_SpawnTroop) override;
+	virtual void Handle(const protocol::commands::TeamChangeCommand& a_TeamChange) override;
+	virtual void Handle(const protocol::commands::UpgradeTowerCommand& a_UpgradeTower) override;
+	virtual void Handle(const protocol::commands::UseItemCommand& a_UseItem) override;
+};
+
+}  // namespace sim
+}  // namespace td

include/td/simulation/ServerSimulation.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <mutex>
+#include <td/game/World.h>
+
+namespace td {
+namespace sim {
+
+// TODO: OnEnd signal
+/**
+ * \note This class is thread safe
+ */
+class ServerSimulation : public protocol::CommandHandler {
+  private:
+	std::mutex m_Mutex;
+	game::World& m_World;
+	std::uint64_t m_StepTime;
+	std::uint64_t m_CurrentTime;
+	std::vector<protocol::LockStep> m_History;
+
+	using protocol::CommandHandler::Handle;
+
+  public:
+	ServerSimulation(game::World& a_World, std::uint64_t a_StepTime);
+
+	protocol::packets::LockStepsPacket Update();
+
+	protocol::packets::LockStepsPacket MakePacket();
+
+	std::vector<protocol::LockStep> GetFirstLocksteps();
+
+	// no checks are done !
+
+	virtual void Handle(const protocol::commands::SpawnTroopCommand& a_SpawnTroop) override;
+	virtual void Handle(const protocol::commands::PlaceTowerCommand& a_PlaceTower) override;
+
+	protocol::packets::LockStepResponsePacket GetResponse(const protocol::packets::LockStepRequestPacket& a_Missing) const;
+};
+
+}  // namespace sim
+}  // namespace td

include/td/simulation/WorldSnapshot.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <td/game/WorldTypes.h>
+#include <td/game/Mobs.h>
+
+namespace td {
+namespace sim {
+
+struct WorldSnapshot {
+	game::MobList m_Mobs;
+
+	game::TowerList m_Towers;
+
+	game::TeamList m_Teams;
+};
+
+}  // namespace sim
+}  // namespace td

include/td/simulation/WorldTicker.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <td/protocol/command/Commands.h>
+#include <td/simulation/WorldSnapshot.h>
+
+namespace td {
+namespace game {
+class World;
+}
+
+namespace sim {
+
+class IWorldSystem {
+  public:
+	virtual void Tick(const game::World& a_World, WorldSnapshot& a_State, FpFloat a_Delta) = 0;
+	virtual ~IWorldSystem() = default;
+};
+
+class WorldTicker {
+  private:
+	std::vector<std::unique_ptr<IWorldSystem>> m_Systems;
+
+  public:
+	WorldTicker();
+
+	WorldSnapshot NextStep(
+		const game::World& a_World, WorldSnapshot& a_PreviousState, const protocol::LockStep& a_LockStep, FpFloat a_Delta);
+
+  private:
+	void ApplySteps(const game::World& a_World, WorldSnapshot& a_State, const protocol::LockStep& a_LockStep);
+	void Tick(const game::World& a_World, WorldSnapshot& a_State, FpFloat a_Delta);
+	WorldSnapshot CreateNext(WorldSnapshot& a_PreviousState);
+
+	template <typename T>
+	void AddSystem() {
+		m_Systems.push_back(std::make_unique<T>());
+	}
+};
+
+}  // namespace sim
+}  // namespace td

include/td/simulation/system/EntityMove.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include <td/simulation/WorldTicker.h>
+
+namespace td {
+namespace sim {
+
+class EntityMove : public IWorldSystem {
+  public:
+	virtual void Tick(const game::World& a_World, WorldSnapshot& a_State, FpFloat a_Delta) override;
+};
+
+}  // namespace sim
+}  // namespace td

src/client/Client.cpp

@@ -0,0 +1,25 @@
+#include <client/Client.h>
+
+#include <client/state/LoggingState.h>
+
+namespace td {
+namespace client {
+
+Client::Client(const std::shared_ptr<IClientSocket>& a_Socket) : m_Socket(a_Socket), m_Players(a_Socket) {
+	// ChangeState<LoggingState>(a_PlayerName);
+}
+
+Client::~Client() {
+	Disconnect();
+}
+
+void Client::SendPacket(const protocol::PacketBase& a_Packet) {
+	m_Socket->Send(a_Packet);
+}
+
+void Client::Disconnect() {
+	m_Socket->Disconnect();
+}
+
+}  // namespace client
+}  // namespace td

src/client/ClientState.cpp

@@ -0,0 +1,16 @@
+#include <client/ClientState.h>
+#include <client/Client.h>
+
+namespace td {
+namespace client {
+
+ClientState::ClientState(Client& a_Client) : Client::State(a_Client) {
+	Connect(m_StateMachine.m_Socket->OnReceive, std::bind(&ClientState::HandleBase, this, std::placeholders::_1));
+}
+
+void ClientState::SendPacket(const protocol::PacketBase& a_Packet) {
+	m_StateMachine.m_Socket->Send(a_Packet);
+}
+
+}  // namespace server
+}  // namespace td

src/client/PlayerManager.cpp

@@ -0,0 +1,44 @@
+#include <client/PlayerManager.h>
+
+#include <client/IClientSocket.h>
+
+#include <iostream>
+
+namespace td {
+namespace client {
+
+PlayerManager::PlayerManager(const std::shared_ptr<IClientSocket>& a_Socket) : m_Socket(a_Socket) {
+	a_Socket->OnReceive.Connect(std::bind(&PlayerManager::HandleBase, this, std::placeholders::_1));
+	OnPlayerJoin.Connect([this](const PlayerInfo& a_Player){
+		std::cout << "[Client " << this << "] " << a_Player.m_PlayerName << " joined !\n";
+	});
+	OnPlayerLeave.Connect([this](const PlayerID a_Player){
+		std::cout << "[Client " << this << "] " << GetPlayer(a_Player).m_PlayerName << "(" << +a_Player << ") left !\n";
+	});
+}
+
+PlayerManager::~PlayerManager() {}
+
+PlayerInfo PlayerManager::GetPlayer(PlayerID a_Player) {
+	return m_Players.at(a_Player);
+}
+
+void PlayerManager::Handle(const protocol::packets::PlayerJoinPacket& a_Packet) {
+	m_Players.emplace(a_Packet->m_Player.m_PlayerId, a_Packet->m_Player);
+	OnPlayerJoin(a_Packet->m_Player);
+}
+
+void PlayerManager::Handle(const protocol::packets::PlayerListPacket& a_Packet) {
+	for (auto pInfo : a_Packet->m_Players) {
+		m_Players.emplace(pInfo.m_PlayerId, pInfo);
+		OnPlayerJoin(pInfo);
+	}
+}
+
+void PlayerManager::Handle(const protocol::packets::PlayerLeavePacket& a_Packet) {
+	OnPlayerLeave(a_Packet->m_PlayerId);
+	m_Players.erase(a_Packet->m_PlayerId);
+}
+
+}  // namespace client
+}  // namespace td

src/client/socket/FakeSocket.cpp

@@ -0,0 +1,23 @@
+#include <client/socket/FakeSocket.h>
+#include <server/socket/FakeSocket.h>
+
+namespace td {
+namespace client {
+
+void FakeSocket::Send(const protocol::PacketBase& a_Packet) {
+	m_Server->OnReceivePeer(m_PeerId, a_Packet);
+}
+
+std::shared_ptr<FakeSocket> FakeSocket::Connect(const std::shared_ptr<server::FakeSocket>& a_Server) {
+	auto socket = std::make_shared<FakeSocket>(Private());
+	socket->m_Server = a_Server;
+	socket->m_PeerId = a_Server->ConnectFakePeer(socket);
+	return socket;
+}
+
+void FakeSocket::Disconnect() {
+	m_Server->DisconnectFakePeer(m_PeerId);
+}
+
+}  // namespace client
+}  // namespace td

src/client/state/GameState.cpp

@@ -0,0 +1,26 @@
+#include <client/state/GameState.h>
+
+namespace td {
+namespace client {
+
+GameState::GameState(Client& a_Client, const std::shared_ptr<game::World>& a_World, std::uint64_t a_StepTime, const std::vector<protocol::LockStep> a_FirstSteps) :
+	ClientState(a_Client), m_World(a_World), m_Simulation(a_World, a_StepTime, a_FirstSteps) {
+	m_Simulation.OnMissingLockSteps.Connect([this](const std::vector<td::StepTime>& a_MissingSteps) {
+		SendPacket(protocol::packets::LockStepRequestPacket(a_MissingSteps));
+	});
+}
+
+void GameState::Handle(const protocol::packets::LockStepsPacket& a_LockStep) {
+	m_Simulation.Handle(a_LockStep);
+}
+
+void GameState::Handle(const protocol::packets::LockStepResponsePacket& a_LockStep) {
+	m_Simulation.Handle(a_LockStep);
+}
+
+void GameState::Update(float a_Delta) {
+	m_CurrentLerp = m_Simulation.Update(a_Delta);
+}
+
+}  // namespace client
+}  // namespace td

src/client/state/LobbyState.cpp

@@ -0,0 +1,27 @@
+#include <client/state/LobbyState.h>
+
+#include <client/state/GameState.h>
+
+namespace td {
+namespace client {
+
+LobbyState::LobbyState(Client& a_Client) : ClientState(a_Client), m_World(std::make_shared<game::World>()) {}
+
+LobbyState::~LobbyState() {}
+
+void LobbyState::Handle(const protocol::packets::WorldHeaderPacket& a_Packet) {
+	m_World->LoadMap(*a_Packet);
+}
+
+void LobbyState::Handle(const protocol::packets::WorldDataPacket& a_Packet) {
+	m_World->LoadMap(*a_Packet);
+}
+
+void LobbyState::Handle(const protocol::packets::BeginGamePacket& a_Packet) {
+	ChangeState<GameState>(m_World, STEP_TIME, a_Packet->m_FirstLocksteps);
+}
+
+void LobbyState::Update(float a_Delta) {}
+
+}  // namespace client
+}  // namespace td

src/client/state/LoggingState.cpp

@@ -0,0 +1,27 @@
+#include <client/state/LoggingState.h>
+
+#include <client/state/LobbyState.h>
+
+namespace td {
+namespace client {
+
+LoggingState::LoggingState(Client& a_Client, const std::string& a_PlayerName) : ClientState(a_Client) {
+	SendPacket(td::protocol::packets::PlayerLoginPacket(a_PlayerName));
+}
+
+void LoggingState::Update(float a_Delta) {
+}
+
+LoggingState::~LoggingState() {}
+
+void LoggingState::Handle(const protocol::packets::PlayerJoinPacket& a_Packet) {
+	// TODO: check if id matches client id
+}
+
+void LoggingState::Handle(const protocol::packets::LoggingSuccessPacket& a_Packet) {
+	m_StateMachine.m_Id = a_Packet->m_PlayerId;
+	ChangeState<LobbyState>();
+}
+
+}  // namespace client
+}  // namespace td

src/main.cpp

@@ -1,224 +1,17 @@
-#include <iostream>
-
-#include <sp/common/DataBuffer.h>
-#include <sp/extensions/Compress.h>
-#include <td/input/Display.h>
-
-#include <td/game/World.h>
-#include <td/protocol/packet/Packets.h>
-
-#include <td/render/renderer/WorldRenderer.h>
-#include <td/render/renderer/EntityRenderer.h>
-
-namespace td {
-namespace game {
-
-sp::DataBuffer& operator>>(sp::DataBuffer& buffer, game::TilePtr& tile) {
-	game::TileType tileType;
-	buffer >> tileType;
-	switch (tileType) {
-		case game::TileType::Tower: {
-			auto tilePtr = std::make_shared<game::TowerTile>();
-			buffer >> tilePtr->color_palette_ref >> tilePtr->team_owner;
-			tile = tilePtr;
-			break;
-		}
-		case game::TileType::Walk: {
-			auto tilePtr = std::make_shared<game::WalkableTile>();
-			buffer >> tilePtr->direction;
-			tile = tilePtr;
-			break;
-		}
-		case game::TileType::Decoration: {
-			auto tilePtr = std::make_shared<game::DecorationTile>();
-			buffer >> tilePtr->color_palette_ref;
-			tile = tilePtr;
-			break;
-		}
-		default:
-			break;
-	}
-	return buffer;
-}
-}  // namespace game
-}  // namespace td
-
-namespace sp {
-namespace details {
-
-template <>
-void ReadMessage(DataBuffer& a_Buffer, td::protocol::pdata::WorldHeader& a_Header) {
-	a_Buffer >> a_Header.m_TowerPlacePalette >> a_Header.m_WalkablePalette;
-
-	std::uint16_t decoPaletteSize;
-	a_Buffer >> decoPaletteSize;
-
-	std::size_t decoPalletteSizeByte = decoPaletteSize * sizeof(td::Color);
-
-	a_Header.m_DecorationPalette.resize(decoPaletteSize);
-
-	memcpy(reinterpret_cast<std::uint8_t*>(a_Header.m_DecorationPalette.data()), a_Buffer.data() + a_Buffer.GetReadOffset(),
-		decoPalletteSizeByte);
-
-	a_Buffer.SetReadOffset(a_Buffer.GetReadOffset() + decoPalletteSizeByte);
-
-	a_Buffer >> a_Header.m_Background;
-
-	td::utils::shape::Rectangle redCastle, blueCastle;
-
-	a_Buffer >> a_Header.m_RedSpawn >> redCastle;
-	a_Buffer >> a_Header.m_BlueSpawn >> blueCastle;
-
-	a_Header.m_RedCastle.SetShape(redCastle);
-	a_Header.m_BlueCastle.SetShape(blueCastle);
-
-	std::uint64_t tilePaletteSize;
-	a_Buffer >> tilePaletteSize;
-
-	a_Header.m_TilePalette.reserve(tilePaletteSize);
-
-	for (std::uint64_t tileNumber = 0; tileNumber < tilePaletteSize; tileNumber++) {
-		td::game::TilePtr tile;
-		a_Buffer >> tile;
-		a_Header.m_TilePalette.push_back(tile);
-	}
-
-	a_Buffer >> a_Header.m_SpawnColorPalette;
-}
-
-typedef std::vector<uint64_t> ChunkPackedData;
-
-const int BITS_IN_BYTE = 8;
-const int BITS_IN_LONG = BITS_IN_BYTE * sizeof(std::uint64_t);
-
-static unsigned int countBits(unsigned int number) {
-	// log function in base 2
-	// take only integer part
-	return static_cast<unsigned int>(std::log2(number) + 1);
-}
-
-
-template <>
-void ReadMessage(DataBuffer& a_Buffer, td::protocol::pdata::WorldData& a_WorldData) {
-	std::uint64_t chunkCount;
-	a_Buffer >> chunkCount;
-
-	for (std::uint64_t chunkNumber = 0; chunkNumber < chunkCount; chunkNumber++) {
-		td::game::ChunkPtr chunk = std::make_shared<td::game::Chunk>();
-
-		td::game::ChunkCoord chunkCoords;
-		a_Buffer >> chunkCoords.x >> chunkCoords.y;
-
-		std::uint64_t chunkPaletteSize;
-		// std::reverse(reinterpret_cast<std::uint8_t*>(&chunkPaletteSize), reinterpret_cast<std::uint8_t*>(&chunkPaletteSize) + 4);
-		a_Buffer >> chunkPaletteSize;
-
-		td::game::ChunkPalette chunkPalette(chunkPaletteSize);
-
-		memcpy(reinterpret_cast<void*>(chunkPalette.data()), a_Buffer.data() + a_Buffer.GetReadOffset(),
-			chunkPaletteSize * sizeof(td::game::ChunkPalette::value_type));
-		a_Buffer.SetReadOffset(a_Buffer.GetReadOffset() + chunkPaletteSize * sizeof(td::game::ChunkPalette::value_type));
-
-		chunk->palette = chunkPalette;
-
-		std::uint8_t bitsPerTile = countBits(chunkPaletteSize);
-
-		// A bitmask that contains bitsPerTile set bits
-		td::game::Chunk::ChunkData::value_type individualValueMask = ((1 << bitsPerTile) - 1);
-
-		ChunkPackedData chunkData(td::game::Chunk::ChunkSize / (BITS_IN_BYTE * sizeof(ChunkPackedData::value_type) / bitsPerTile), 0);
-
-		memcpy(reinterpret_cast<void*>(chunkData.data()), a_Buffer.data() + a_Buffer.GetReadOffset(),
-			chunkData.size() * sizeof(ChunkPackedData::value_type));
-		a_Buffer.SetReadOffset(a_Buffer.GetReadOffset() + chunkData.size() * sizeof(ChunkPackedData::value_type));
-
-		for (unsigned int tileNumber = 0; tileNumber < td::game::Chunk::ChunkSize; tileNumber++) {
-			std::size_t startLong = (tileNumber * bitsPerTile) / BITS_IN_LONG;
-			std::size_t startOffset = (tileNumber * bitsPerTile) % BITS_IN_LONG;
-			std::size_t endLong = ((tileNumber + 1) * bitsPerTile - 1) / BITS_IN_LONG;
-
-			td::game::Chunk::ChunkData::value_type value;
-			if (startLong == endLong) {
-				value = (chunkData[startLong] >> startOffset);
-			} else {
-				int endOffset = BITS_IN_LONG - startOffset;
-				value = (chunkData[startLong] >> startOffset | chunkData[endLong] << endOffset);
-			}
-			value &= individualValueMask;
-
-			chunk->tiles[tileNumber] = value;
-		}
-		a_WorldData.m_Chunks.insert({chunkCoords, chunk});
-	}
-}
-
-}  // namespace details
-}  // namespace sp
-
-class WorldApply : public td::protocol::PacketHandler {
-  private:
-	td::game::World& m_World;
-  public:
-	WorldApply(td::game::World& a_World) : m_World(a_World) {}
-
-	void Handle(const td::protocol::pdata::WorldHeader& a_Header) override {
-		m_World.LoadMap(a_Header);
-	}
-	void Handle(const td::protocol::pdata::WorldData& a_Data) override {
-		m_World.LoadMap(a_Data);
-	}
-};
-
-td::game::World GetWorld() {
-sp::DataBuffer buffer;
-	buffer.ReadFile("test/tdmap.tdmap2");
-
-	sp::DataBuffer buffer1 = sp::zlib::Decompress(buffer, 84);
-	buffer.SetReadOffset(buffer.GetReadOffset() + 83);
-	sp::DataBuffer buffer2 = sp::zlib::Decompress(buffer, 511);
-
-	td::protocol::packets::WorldHeaderPacket header;
-	header.Read(buffer1);
-
-	td::protocol::packets::WorldDataPacket data;
-	data.Read(buffer2);
-
-	td::game::World w;
-	WorldApply wa(w);
-
-	td::protocol::PacketDispatcher d;
-	d.RegisterHandler(td::protocol::PacketID::WorldData, &wa);
-	d.RegisterHandler(td::protocol::PacketID::WorldHeader, &wa);
-
-	d.Dispatch(header);
-	d.Dispatch(data);
-
-	return w;
-}
+#include <chrono>
+#include <td/display/state/MainMenuState.h>
+#include <td/misc/Time.h>
 
 int main(int argc, char** argv) {
-	td::game::World w = GetWorld();
-
 	// init GL context
 	td::Display display(1920, 1080, "Tower-Defense 2");
 
-	td::render::Camera cam;
-
-	auto mob = std::make_shared<td::game::Zombie>(0, 0, 0);
-	mob->SetCenter({77, 13});
-	w.GetMobList().push_back(mob);
-
-	td::render::RenderPipeline renderer;
-	renderer.AddRenderer<td::render::WorldRenderer>(cam, w);
-	renderer.AddRenderer<td::render::EntityRenderer>(cam, w);
-
-	cam.SetCamPos({77, 25, 13});
-	cam.UpdatePerspective(display.GetAspectRatio());
+	display.ChangeState<td::MainMenuState>();
 
+	td::Timer timer;
 	while (!display.IsCloseRequested()) {
 		display.PollEvents();
-		renderer.Render();
-		display.Update();
+		display.Update(timer.GetDelta());
 	}
 
 	return 0;

src/server/IServerSocket.cpp

@@ -0,0 +1,56 @@
+#include <server/IServerSocket.h>
+
+namespace td {
+namespace server {
+
+IServerSocket::IServerSocket() {
+}
+
+void IServerSocket::RegisterHandler(const PlayerPacketHandler& a_Handler) {
+	m_Handlers.push_back(a_Handler);
+}
+
+void IServerSocket::UnregisterHandler(const PlayerPacketHandler& a_Handler) {
+	auto it = std::find_if(m_Handlers.begin(), m_Handlers.end(),
+		[&a_Handler](PlayerPacketHandler& handler) { return a_Handler.template target<PlayerPacketHandlerType>() == handler.template target<PlayerPacketHandlerType>(); });
+	m_Handlers.erase(it);
+}
+
+void IServerSocket::OnConnectPeer(PeerID a_PeerId) {
+	// here, the client is not a player yet (we need to wait for auth)
+	m_Ids.AddConnection(a_PeerId);
+	OnPlayerConnect(m_Ids.GetPlayerId(a_PeerId));
+}
+
+void IServerSocket::OnDisconnectPeer(PeerID a_PeerId) {
+	OnPlayerDisconnect(m_Ids.GetPlayerId(a_PeerId));
+	m_Ids.RemovePeer(a_PeerId);
+}
+
+void IServerSocket::OnReceivePeer(PeerID a_PeerId, const protocol::PacketBase& a_Packet) {
+	auto playerId = m_Ids.GetPlayerId(a_PeerId);
+
+	for (const auto& factory : m_Handlers) {
+		auto handler = factory(playerId);
+		a_Packet.Dispatch(*handler);
+	}
+
+	OnReceive(playerId, a_Packet);
+}
+
+void IServerSocket::Send(PlayerID a_PlayerId, const protocol::PacketBase& a_Packet) {
+	SendPeer(m_Ids.GetPeerId(a_PlayerId), a_Packet);
+}
+
+void IServerSocket::Broadcast(const protocol::PacketBase& a_Packet) {
+	for (auto [peerId, playerId] : m_Ids) {
+		SendPeer(peerId, a_Packet);
+	}
+}
+
+void IServerSocket::Disconnect(PlayerID a_PlayerId) {
+	OnDisconnectPeer(m_Ids.GetPeerId(a_PlayerId));
+}
+
+}  // namespace server
+}  // namespace td

src/server/PlayerManager.cpp

@@ -0,0 +1,62 @@
+#include <server/PlayerManager.h>
+
+#include <iostream>
+#include <server/IServerSocket.h>
+
+namespace td {
+namespace server {
+
+PlayerManager::ConnectionHandler::ConnectionHandler(PlayerManager& a_PlayerManager, PlayerID a_Player) :
+	m_PlayerManager(a_PlayerManager), m_Player(a_Player) {}
+
+void PlayerManager::ConnectionHandler::Handle(const protocol::packets::PlayerLoginPacket& a_Packet) {
+	PlayerInfo pInfo{m_Player, a_Packet->m_PlayerName};
+
+	auto& socket = *m_PlayerManager.m_Socket;
+	auto& players = m_PlayerManager.m_Players;
+
+	std::vector<PlayerInfo> playerInfos;
+	playerInfos.reserve(players.size());
+	for (auto& [id, player] : players) {
+		playerInfos.push_back(player);
+	}
+
+	socket.Send(m_Player, protocol::packets::LoggingSuccessPacket(m_Player));
+	socket.Send(m_Player, protocol::packets::PlayerListPacket(playerInfos));
+	socket.Broadcast(protocol::packets::PlayerJoinPacket(pInfo));
+
+	players.emplace(m_Player, pInfo);
+	m_PlayerManager.OnPlayerJoin(m_Player, pInfo);
+	std::cout << "[Server] " << a_Packet->m_PlayerName << " joined !\n";
+}
+
+void PlayerManager::ConnectionHandler::Handle(const protocol::packets::DisconnectPacket& a_Packet) {
+	m_PlayerManager.Disconnect(m_Player);
+}
+
+PlayerManager::PlayerManager(const std::shared_ptr<IServerSocket>& a_Socket) : m_Socket(a_Socket) {
+	a_Socket->RegisterHandler([this](PlayerID a_PlayerId) { return std::make_unique<ConnectionHandler>(*this, a_PlayerId); });
+	a_Socket->OnPlayerDisconnect.Connect(std::bind(&PlayerManager::Disconnect, this, std::placeholders::_1));
+}
+
+void PlayerManager::Disconnect(PlayerID a_Player) {
+	if (!m_Players.contains(a_Player))
+		return;
+	std::cout << "[Server] " << +a_Player << " wants to disconnect !\n";
+	m_Socket->Broadcast(protocol::packets::PlayerLeavePacket(a_Player));
+	m_Players.erase(a_Player);
+}
+
+PlayerManager::~PlayerManager() {}
+
+void PlayerManager::RemovePlayer(PlayerID a_Player) {
+	m_Socket->Disconnect(a_Player);
+	Disconnect(a_Player);
+}
+
+PlayerInfo PlayerManager::GetPlayer(PlayerID a_Player) {
+	return m_Players.at(a_Player);
+}
+
+}  // namespace server
+}  // namespace td

src/server/Server.cpp

@@ -0,0 +1,22 @@
+#include <server/Server.h>
+
+#include <chrono>
+
+#include <server/state/LobbyState.h>
+
+namespace td {
+namespace server {
+
+Server::Server(const std::shared_ptr<IServerSocket>& a_Socket) : m_Socket(a_Socket), m_Players(a_Socket), m_LastMspt(0) {
+	ChangeState<LobbyState>();
+}
+
+void Server::Update(float a_Delta) {
+	auto before = std::chrono::system_clock::now();
+	StateMachine<Server, void, float>::Update(a_Delta);
+	m_LastMspt = std::chrono::duration<float, std::chrono::milliseconds::period>(std::chrono::system_clock::now() - before).count();
+	// std::cout << "Tick : " << m_LastMspt << "ms\n";
+}
+
+}  // namespace server
+}  // namespace td

src/server/ServerState.cpp

@@ -0,0 +1,26 @@
+#include <server/Server.h>
+#include <server/ServerState.h>
+
+#include <td/common/StateMachine.h>
+
+namespace td {
+namespace server {
+
+ServerState::ServerState(Server& a_Server) : Server::State(a_Server) {
+	Connect(m_StateMachine.m_Socket->OnReceive, std::bind(&ServerState::HandlePacket, this, std::placeholders::_1, std::placeholders::_2));
+	Connect(m_StateMachine.m_Players.OnPlayerJoin, std::bind(&ServerState::OnPlayerJoin, this, std::placeholders::_1, std::placeholders::_2));
+	Connect(m_StateMachine.m_Players.OnPlayerLeave, std::bind(&ServerState::OnPlayerLeave, this, std::placeholders::_1));
+}
+
+ServerState::~ServerState() {}
+
+void ServerState::SendPacket(PlayerID a_Id, const protocol::PacketBase& a_Packet) {
+	m_StateMachine.m_Socket->Send(a_Id, a_Packet);
+}
+
+void ServerState::BroadcastPacket(const protocol::PacketBase& a_Packet) {
+	m_StateMachine.m_Socket->Broadcast(a_Packet);
+}
+
+}  // namespace server
+}  // namespace td

src/server/socket/FakeSocket.cpp

@@ -0,0 +1,48 @@
+#include <server/socket/FakeSocket.h>
+
+namespace td {
+namespace server {
+
+void FakeSocket::SendPeer(PeerID a_Peer, const protocol::PacketBase& a_Packet) {
+	auto socket = m_Clients.at(a_Peer);
+	assert(socket.has_value());
+	assert(!socket.value().expired());
+	socket.value().lock()->OnReceive(a_Packet);
+}
+
+void FakeSocket::ReceiveFromFakePeer(PeerID a_Peer, const protocol::PacketBase& a_Packet) {
+	OnReceivePeer(a_Peer, a_Packet);
+}
+
+PeerID FakeSocket::ConnectFakePeer(const std::shared_ptr<client::FakeSocket>& a_Socket) {
+	int peerId = GetNextFreeId();
+	if (peerId == -1) {
+		peerId = m_Clients.size();
+		m_Clients.push_back(a_Socket);
+	} else {
+		m_Clients.emplace(m_Clients.begin() + peerId, a_Socket);
+	}
+	a_Socket->OnConnect();
+	OnConnectPeer(peerId);
+	return peerId;
+}
+
+void FakeSocket::DisconnectFakePeer(PeerID a_Peer) {
+	auto socket = m_Clients.at(a_Peer);
+	assert(socket.has_value());
+	assert(!socket.value().expired());
+	socket.value().lock()->OnDisconnect();
+	OnDisconnectPeer(a_Peer);
+}
+
+int FakeSocket::GetNextFreeId() {
+	auto it = std::find_if(m_Clients.begin(), m_Clients.end(), [](const auto& a_Value) { return !a_Value.has_value(); });
+
+	if (it == m_Clients.end())
+		return -1;
+
+	return std::distance(m_Clients.begin(), it);
+}
+
+}  // namespace server
+}  // namespace td

src/server/state/GameState.cpp

@@ -0,0 +1,47 @@
+#include <server/state/GameState.h>
+#include <server/state/GameStateHandler.h>
+#include <td/protocol/packet/PacketSerialize.h>
+
+#include <iostream>
+
+namespace td {
+namespace server {
+
+GameState::GameState(Server& a_Server, const std::shared_ptr<game::World>& a_World) :
+	ServerState(a_Server), m_World(a_World), m_Simulation(*m_World, STEP_TIME), m_Time(0) {
+	std::cout << "[Server] Switched to Game state !\n";
+	BroadcastPacket(a_World->GetPacketHeader());
+	BroadcastPacket(a_World->GetPacketData());
+	BroadcastPacket(protocol::packets::BeginGamePacket());
+	BroadcastPacket(m_Simulation.MakePacket());
+}
+
+void GameState::HandlePacket(PlayerID a_Id, const protocol::PacketBase& a_Packet) {
+	GameStateHandler handler(*this, a_Id);
+	a_Packet.Dispatch(handler);
+}
+
+void GameState::Update(float a_Delta) {
+	// TODO: don't make STEP_TIME constant
+	static const float stepTimeSecond = static_cast<float>(STEP_TIME) / 1000.0f;
+	m_Time += a_Delta;
+	if (m_Time > stepTimeSecond) {
+		m_Time = std::fmod(m_Time, stepTimeSecond);
+		auto lockStepPacket = m_Simulation.Update();
+		BroadcastPacket(lockStepPacket);
+	}
+}
+
+void GameState::OnPlayerJoin(PlayerID a_Id, const td::PlayerInfo& a_Info) {
+	SendPacket(a_Id, m_World->GetPacketHeader());
+	SendPacket(a_Id, m_World->GetPacketData());
+
+	// TODO: real teams
+	std::vector<PlayerInfo> team;
+	std::vector<protocol::LockStep> locksteps = m_Simulation.GetFirstLocksteps();
+
+	BroadcastPacket(protocol::packets::BeginGamePacket(team, team, locksteps));
+}
+
+}  // namespace server
+}  // namespace td

src/server/state/GameStateHandler.cpp

@@ -0,0 +1,28 @@
+#include <server/state/GameState.h>
+#include <server/state/GameStateHandler.h>
+
+namespace td {
+namespace server {
+
+GameStateHandler::GameStateHandler(GameState& a_GameState, PlayerID a_PlayerId) : m_GameState(a_GameState), m_PlayerId(a_PlayerId) {}
+
+// TODO: redo this
+void GameStateHandler::Handle(const protocol::packets::SpawnTroopPacket& a_Packet) {
+	static const EntityCoords DEFAULT_POS(td::FpFloat(77), td::FpFloat(13));
+
+	td::protocol::commands::SpawnTroopCommand spawn(*a_Packet->m_Type, *a_Packet->m_Level, DEFAULT_POS, m_PlayerId);
+	m_GameState.m_Simulation.Handle(spawn);
+}
+
+// TODO: and this
+void GameStateHandler::Handle(const protocol::packets::PlaceTowerPacket& a_Packet) {
+	td::protocol::commands::PlaceTowerCommand place(a_Packet->m_Type, m_PlayerId, a_Packet->m_Position);
+	m_GameState.m_Simulation.Handle(place);
+}
+
+void GameStateHandler::Handle(const protocol::packets::LockStepRequestPacket& a_Packet) {
+	m_GameState.SendPacket(m_PlayerId, m_GameState.m_Simulation.GetResponse(a_Packet));
+}
+
+}  // namespace server
+}  // namespace td

src/server/state/LobbyState.cpp

@@ -0,0 +1,60 @@
+#include <server/state/GameState.h>
+#include <server/state/LobbyState.h>
+
+#include <iostream>
+#include <fstream>
+#include <td/protocol/packet/PacketSerialize.h>
+
+#include <sp/common/DataBuffer.h>
+#include <sp/extensions/Compress.h>
+#include <sp/io/MessageStream.h>
+#include <sp/io/StdIo.h>
+
+namespace td {
+namespace server {
+
+void Save(const protocol::PacketBase& header, const protocol::PacketBase& data) {
+	auto comp = std::make_shared<sp::ZlibCompress>();
+
+	std::ofstream fStream("test/tdmap.tdmap3");
+	auto out = std::make_shared<sp::StdOuput>(fStream);
+
+	sp::MessageStream<protocol::PacketFactory> stream(std::move(out), std::move(comp));
+
+	stream.WriteMessage(header, false);
+	stream.WriteMessage(data, false);
+}
+
+game::WorldPtr GetWorld() {
+	auto comp = std::make_shared<sp::ZlibCompress>();
+
+	std::ifstream fStream("test/tdmap.tdmap2");
+	auto out = std::make_shared<sp::StdInput>(fStream);
+
+	sp::MessageStream<protocol::PacketFactory> stream(std::move(out), std::move(comp));
+
+	auto header = stream.ReadConcreteMessage<protocol::packets::WorldHeaderPacket>();
+	auto data = stream.ReadConcreteMessage<protocol::packets::WorldDataPacket>();
+
+	auto w = std::make_shared<game::World>();
+
+	w->LoadMap(**header);
+	w->LoadMap(**data);
+
+	// Save(*header, *data);
+
+	return w;
+}
+
+LobbyState::LobbyState(Server& a_Server) : ServerState(a_Server) {}
+
+void LobbyState::HandlePacket(PlayerID a_Id, const protocol::PacketBase& a_Packet) {}
+
+void LobbyState::OnPlayerJoin(PlayerID a_Id, const td::PlayerInfo& a_Info) {
+	m_StateMachine.ChangeState<GameState>(GetWorld());
+}
+
+void LobbyState::Update(float a_Delta) {}
+
+}  // namespace server
+}  // namespace td

src/td/Types.cpp

@@ -0,0 +1,29 @@
+#include <td/Types.h>
+
+#include <sp/common/DataBuffer.h>
+#include <sp/common/ByteSwapping.h>
+#include <sp/common/DataBufferOperators.h>
+
+namespace td {
+
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const EntityCoords& a_Coords) {
+	return a_Buffer << a_Coords.x << a_Coords.y;
+}
+
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const FpFloat& a_Float) {
+	auto raw = a_Float.raw_value();
+	return a_Buffer << raw;
+}
+
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, EntityCoords& a_Coords) {
+	return a_Buffer >> a_Coords.x >> a_Coords.y;
+}
+
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, FpFloat& a_Float) {
+	auto raw = a_Float.raw_value();
+	a_Buffer >> raw;
+	a_Float = FpFloat::from_raw_value(raw);
+	return a_Buffer;
+}
+
+}  // namespace td

src/td/display/Display.cpp

@@ -1,4 +1,4 @@
-#include <td/input/Display.h>
+#include <td/display/Display.h>
 
 #include <GL/glew.h>
 #include <SDL3/SDL.h>
@@ -8,11 +8,15 @@
 
 #include <td/misc/Format.h>
 #include <td/misc/Log.h>
+#include <td/display/ImGuiTheme.h>
 
 namespace td {
 
 Display::Display(int a_Width, int a_Height, const std::string& a_Title) :
 	m_LastWidth(0), m_LastHeight(0), m_AspectRatio(1), m_ShouldClose(false) {
+	if (!SDL_Init(SDL_INIT_VIDEO)) {
+		utils::LOGE(utils::Format("Could not initialize SDL! SDL error: %s", SDL_GetError()));
+	}
 
 	m_Window = SDL_CreateWindow(a_Title.c_str(), a_Width, a_Height, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
 
@@ -38,6 +42,9 @@ Display::Display(int a_Width, int a_Height, const std::string& a_Title) :
 	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
 	SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
 
+	SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
+	SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 8);
+
 	m_GLContext = SDL_GL_CreateContext(m_Window);
 
 	if (!m_GLContext) {
@@ -46,6 +53,8 @@ Display::Display(int a_Width, int a_Height, const std::string& a_Title) :
 
 	int major, minor, mask;
 	int r, g, b, a, depth;
+	int mBuffers, mSamples;
+
 	SDL_GL_GetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, &mask);
 	SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &major);
 	SDL_GL_GetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, &minor);
@@ -57,6 +66,9 @@ Display::Display(int a_Width, int a_Height, const std::string& a_Title) :
 
 	SDL_GL_GetAttribute(SDL_GL_DEPTH_SIZE, &depth);
 
+	SDL_GL_GetAttribute(SDL_GL_MULTISAMPLEBUFFERS, &mBuffers);
+	SDL_GL_GetAttribute(SDL_GL_MULTISAMPLESAMPLES, &mSamples);
+
 	const char* mask_desc;
 
 	if (mask & SDL_GL_CONTEXT_PROFILE_CORE) {
@@ -72,6 +84,8 @@ Display::Display(int a_Width, int a_Height, const std::string& a_Title) :
 	utils::LOG(utils::Format(
 		"GL Context : %i.%i %s, Color : R:%i G:%i B:%i A:%i, Depth bits : %i", major, minor, mask_desc, r, g, b, a, depth));
 
+	utils::LOG(utils::Format("MultiSamples : Buffers : %i, Samples : %i", mBuffers, mSamples));
+
 	SDL_GL_MakeCurrent(m_Window, m_GLContext);
 
 	GLenum error = glewInit();
@@ -81,6 +95,9 @@ Display::Display(int a_Width, int a_Height, const std::string& a_Title) :
 
 	// WindowResizeEvent(WindowWidth, WindowHeight);
 
+	// vsync
+	SDL_GL_SetSwapInterval(1);
+
 	// Setup Dear ImGui context
 	IMGUI_CHECKVERSION();
 	ImGui::CreateContext();
@@ -96,9 +113,11 @@ Display::Display(int a_Width, int a_Height, const std::string& a_Title) :
 	// Setup scaling
 	float main_scale = SDL_GetDisplayContentScale(SDL_GetPrimaryDisplay());
 	// ImGuiStyle& style = ImGui::GetStyle();
-	// style.ScaleAllSizes(main_scale);  // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this
+	// style.ScaleAllSizes(main_scale);  // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing
+	// this
 	// 								  // requires resetting Style + calling this again)
-	// style.FontSizeBase = 13 * main_scale;  // Set initial font scale. (using io.ConfigDpiScaleFonts=true makes this unnecessary. We leave
+	// style.FontSizeBase = 13 * main_scale;  // Set initial font scale. (using io.ConfigDpiScaleFonts=true makes this unnecessary. We
+	// leave
 	// 								  // both here for documentation purpose)
 
 
@@ -109,8 +128,12 @@ Display::Display(int a_Width, int a_Height, const std::string& a_Title) :
 	// Setup Platform/Renderer backends
 	ImGui_ImplSDL3_InitForOpenGL(m_Window, m_GLContext);
 	ImGui_ImplOpenGL3_Init("#version 330");
+	LoadTheme();
 }
 
+void Display::Close() {
+	m_ShouldClose = true;
+}
 
 void Display::PollEvents() {
 	SDL_Event event;
@@ -119,12 +142,21 @@ void Display::PollEvents() {
 			case SDL_EVENT_QUIT:
 			case SDL_EVENT_WINDOW_CLOSE_REQUESTED: {
 				m_ShouldClose = true;
+				break;
 			}
 
 			case SDL_EVENT_WINDOW_RESIZED: {
 				m_LastWidth = event.window.data1;
 				m_LastHeight = event.window.data2;
 				m_AspectRatio = (float)m_LastWidth / m_LastHeight;
+				OnAspectRatioChange(m_AspectRatio);
+				break;
+			}
+
+			case SDL_EVENT_KEY_DOWN: {
+				if (!event.key.repeat)
+					OnKeyDown(event.key.key);
+				break;
 			}
 
 			default:
@@ -138,7 +170,11 @@ void Display::PollEvents() {
 	ImGui::NewFrame();
 }
 
-void Display::Update() {
+void Display::Update(float a_Delta) {
+	StateMachine::Update(a_Delta);
+#ifndef NDEBUG
+	ImGui::ShowDemoWindow();
+#endif
 	ImGui::Render();
 	ImGuiIO& io = ImGui::GetIO();
 	glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);

src/td/display/DisplayState.cpp

@@ -0,0 +1,10 @@
+#include <td/display/DisplayState.h>
+
+namespace td {
+
+DisplayState::DisplayState(Display& a_Display) : Display::State(a_Display) {
+	Connect(m_StateMachine.OnKeyDown, std::bind(&DisplayState::OnKeyDown, this, std::placeholders::_1));
+	Connect(m_StateMachine.OnAspectRatioChange, std::bind(&DisplayState::OnAspectRatioChange, this, std::placeholders::_1));
+}
+
+}  // namespace td

src/td/display/ImGuiTheme.cpp

@@ -0,0 +1,88 @@
+#include <td/display/ImGuiTheme.h>
+
+#include <imgui.h>
+
+namespace td {
+
+void LoadTheme() {
+
+	static const bool bStyleDark_ = true;
+	static const float alpha_ = 0.8f;
+
+	ImGuiStyle& style = ImGui::GetStyle();
+
+	// light style from Pacôme Danhiez (user itamago) https://github.com/ocornut/imgui/pull/511#issuecomment-175719267
+	style.Alpha = 1.0f;
+	style.FrameRounding = 3.0f;
+	style.Colors[ImGuiCol_Text] = ImVec4(0.00f, 0.00f, 0.00f, 1.00f);
+	style.Colors[ImGuiCol_TextDisabled] = ImVec4(0.60f, 0.60f, 0.60f, 1.00f);
+	style.Colors[ImGuiCol_WindowBg] = ImVec4(0.94f, 0.94f, 0.94f, 0.94f);
+	// style.Colors[ImGuiCol_ChildWindowBg] = ImVec4(0.00f, 0.00f, 0.00f, 0.00f);
+	style.Colors[ImGuiCol_PopupBg] = ImVec4(1.00f, 1.00f, 1.00f, 0.94f);
+	style.Colors[ImGuiCol_Border] = ImVec4(0.00f, 0.00f, 0.00f, 0.39f);
+	style.Colors[ImGuiCol_BorderShadow] = ImVec4(1.00f, 1.00f, 1.00f, 0.10f);
+	style.Colors[ImGuiCol_FrameBg] = ImVec4(1.00f, 1.00f, 1.00f, 0.94f);
+	style.Colors[ImGuiCol_FrameBgHovered] = ImVec4(0.26f, 0.59f, 0.98f, 0.40f);
+	style.Colors[ImGuiCol_FrameBgActive] = ImVec4(0.26f, 0.59f, 0.98f, 0.67f);
+	style.Colors[ImGuiCol_TitleBg] = ImVec4(0.96f, 0.96f, 0.96f, 1.00f);
+	style.Colors[ImGuiCol_TitleBgCollapsed] = ImVec4(1.00f, 1.00f, 1.00f, 0.51f);
+	style.Colors[ImGuiCol_TitleBgActive] = ImVec4(0.82f, 0.82f, 0.82f, 1.00f);
+	style.Colors[ImGuiCol_MenuBarBg] = ImVec4(0.86f, 0.86f, 0.86f, 1.00f);
+	style.Colors[ImGuiCol_ScrollbarBg] = ImVec4(0.98f, 0.98f, 0.98f, 0.53f);
+	style.Colors[ImGuiCol_ScrollbarGrab] = ImVec4(0.69f, 0.69f, 0.69f, 1.00f);
+	style.Colors[ImGuiCol_ScrollbarGrabHovered] = ImVec4(0.59f, 0.59f, 0.59f, 1.00f);
+	style.Colors[ImGuiCol_ScrollbarGrabActive] = ImVec4(0.49f, 0.49f, 0.49f, 1.00f);
+	// style.Colors[ImGuiCol_ComboBg] = ImVec4(0.86f, 0.86f, 0.86f, 0.99f);
+	style.Colors[ImGuiCol_CheckMark] = ImVec4(0.26f, 0.59f, 0.98f, 1.00f);
+	style.Colors[ImGuiCol_SliderGrab] = ImVec4(0.24f, 0.52f, 0.88f, 1.00f);
+	style.Colors[ImGuiCol_SliderGrabActive] = ImVec4(0.26f, 0.59f, 0.98f, 1.00f);
+	style.Colors[ImGuiCol_Button] = ImVec4(0.26f, 0.59f, 0.98f, 0.40f);
+	style.Colors[ImGuiCol_ButtonHovered] = ImVec4(0.26f, 0.59f, 0.98f, 1.00f);
+	style.Colors[ImGuiCol_ButtonActive] = ImVec4(0.06f, 0.53f, 0.98f, 1.00f);
+	style.Colors[ImGuiCol_Header] = ImVec4(0.26f, 0.59f, 0.98f, 0.31f);
+	style.Colors[ImGuiCol_HeaderHovered] = ImVec4(0.26f, 0.59f, 0.98f, 0.80f);
+	style.Colors[ImGuiCol_HeaderActive] = ImVec4(0.26f, 0.59f, 0.98f, 1.00f);
+	// style.Colors[ImGuiCol_Column] = ImVec4(0.39f, 0.39f, 0.39f, 1.00f);
+	// style.Colors[ImGuiCol_ColumnHovered] = ImVec4(0.26f, 0.59f, 0.98f, 0.78f);
+	// style.Colors[ImGuiCol_ColumnActive] = ImVec4(0.26f, 0.59f, 0.98f, 1.00f);
+	style.Colors[ImGuiCol_ResizeGrip] = ImVec4(1.00f, 1.00f, 1.00f, 0.50f);
+	style.Colors[ImGuiCol_ResizeGripHovered] = ImVec4(0.26f, 0.59f, 0.98f, 0.67f);
+	style.Colors[ImGuiCol_ResizeGripActive] = ImVec4(0.26f, 0.59f, 0.98f, 0.95f);
+	// style.Colors[ImGuiCol_CloseButton] = ImVec4(0.59f, 0.59f, 0.59f, 0.50f);
+	// style.Colors[ImGuiCol_CloseButtonHovered] = ImVec4(0.98f, 0.39f, 0.36f, 1.00f);
+	// style.Colors[ImGuiCol_CloseButtonActive] = ImVec4(0.98f, 0.39f, 0.36f, 1.00f);
+	style.Colors[ImGuiCol_PlotLines] = ImVec4(0.39f, 0.39f, 0.39f, 1.00f);
+	style.Colors[ImGuiCol_PlotLinesHovered] = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
+	style.Colors[ImGuiCol_PlotHistogram] = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
+	style.Colors[ImGuiCol_PlotHistogramHovered] = ImVec4(1.00f, 0.60f, 0.00f, 1.00f);
+	style.Colors[ImGuiCol_TextSelectedBg] = ImVec4(0.26f, 0.59f, 0.98f, 0.35f);
+	// style.Colors[ImGuiCol_ModalWindowDarkening] = ImVec4(0.20f, 0.20f, 0.20f, 0.35f);
+
+	if (bStyleDark_) {
+		for (int i = 0; i <= ImGuiCol_COUNT; i++) {
+			ImVec4& col = style.Colors[i];
+			float H, S, V;
+			ImGui::ColorConvertRGBtoHSV(col.x, col.y, col.z, H, S, V);
+
+			if (S < 0.1f) {
+				V = 1.0f - V;
+			}
+			ImGui::ColorConvertHSVtoRGB(H, S, V, col.x, col.y, col.z);
+			if (col.w < 1.00f) {
+				col.w *= alpha_;
+			}
+		}
+	} else {
+		for (int i = 0; i <= ImGuiCol_COUNT; i++) {
+			ImVec4& col = style.Colors[i];
+			if (col.w < 1.00f) {
+				col.x *= alpha_;
+				col.y *= alpha_;
+				col.z *= alpha_;
+				col.w *= alpha_;
+			}
+		}
+	}
+}
+
+}  // namespace td

src/td/display/menu/CreatePartyMenu.cpp

@@ -0,0 +1,16 @@
+#include <td/display/menu/CreatePartyMenu.h>
+
+#include <imgui.h>
+
+namespace td {
+
+CreatePartyMenu::CreatePartyMenu(MainMenuState& a_MainMenu) : MainMenuState::Menu(a_MainMenu) {}
+
+CreatePartyMenu::~CreatePartyMenu() {}
+
+void CreatePartyMenu::Update() {
+	ImGui::Text("CreatePartyMenu");
+	m_StateStack.RenderBackButton();
+}
+
+}  // namespace td

src/td/display/menu/JoinPartyMenu.cpp

@@ -0,0 +1,16 @@
+#include <td/display/menu/JoinPartyMenu.h>
+
+#include <imgui.h>
+
+namespace td {
+
+JoinPartyMenu::JoinPartyMenu(MainMenuState& a_MainMenu) : MainMenuState::Menu(a_MainMenu) {}
+
+JoinPartyMenu::~JoinPartyMenu() {}
+
+void JoinPartyMenu::Update() {
+	ImGui::Text("JoinPartyMenu");
+	m_StateStack.RenderBackButton();
+}
+
+}  // namespace td

src/td/display/menu/MainMenu.cpp

@@ -0,0 +1,28 @@
+#include <td/display/menu/MainMenu.h>
+
+#include <imgui.h>
+#include <td/display/menu/CreatePartyMenu.h>
+#include <td/display/menu/JoinPartyMenu.h>
+#include <td/display/menu/SettingsMenu.h>
+#include <td/display/state/DebugWorldState.h>
+
+namespace td {
+
+MainMenu::MainMenu(MainMenuState& a_MainMenu) : MainMenuState::Menu(a_MainMenu) {}
+
+MainMenu::~MainMenu() {}
+
+void MainMenu::Update() {
+	if (ImGui::Button("Create Party"))
+		m_StateStack.PushState<CreatePartyMenu>();
+	if (ImGui::Button("Join Party"))
+		m_StateStack.PushState<JoinPartyMenu>();
+	if (ImGui::Button("Settings"))
+		m_StateStack.PushState<SettingsMenu>();
+#ifndef NDEBUG
+	if (ImGui::Button("Debug world"))
+		m_StateStack.ChangeState<DebugWorldState>();
+#endif
+}
+
+}  // namespace td

src/td/display/menu/SettingsMenu.cpp

@@ -0,0 +1,16 @@
+#include <td/display/menu/SettingsMenu.h>
+
+#include <imgui.h>
+
+namespace td {
+
+SettingsMenu::SettingsMenu(MainMenuState& a_MainMenu) : MainMenuState::Menu(a_MainMenu) {}
+
+SettingsMenu::~SettingsMenu() {}
+
+void SettingsMenu::Update() {
+	ImGui::Text("SettingsMenu");
+	m_StateStack.RenderBackButton();
+}
+
+}  // namespace td

src/td/display/state/DebugWorldState.cpp

@@ -0,0 +1,104 @@
+#include <td/display/state/DebugWorldState.h>
+
+#include <chrono>
+#include <iostream>
+
+#include <td/game/World.h>
+#include <td/protocol/packet/Packets.h>
+#include <td/render/renderer/EntityRenderer.h>
+#include <td/render/renderer/PlayerListRenderer.h>
+#include <td/render/renderer/TowerRenderer.h>
+#include <td/render/renderer/WorldRenderer.h>
+
+#include <server/Server.h>
+#include <server/socket/FakeSocket.h>
+#include <server/state/LobbyState.h>
+
+#include <client/Client.h>
+#include <client/socket/FakeSocket.h>
+#include <client/state/GameState.h>
+#include <client/state/LoggingState.h>
+
+#include <td/display/Display.h>
+#include <td/display/state/DebugWorldState.h>
+
+namespace td {
+
+DebugWorldState::DebugWorldState(Display& a_Display) : DisplayState(a_Display) {
+	// server
+	m_ServerSocket = std::make_shared<server::FakeSocket>();
+	m_Server = std::make_unique<server::Server>(m_ServerSocket);
+
+	// client
+	auto clientFakeSocket = client::FakeSocket::Connect(m_ServerSocket);
+	m_Client = std::make_unique<client::Client>(clientFakeSocket);
+
+	// TODO: make it better
+	m_Client->OnStateChange.Connect([this](client::Client::State& a_State) {
+		if (auto gameState = dynamic_cast<client::GameState*>(&a_State)) {
+			// render
+			auto clientWorld = gameState->GetWorld();
+			m_Renderer.AddRenderer<render::WorldRenderer>(m_Camera, clientWorld);
+			m_Renderer.AddRenderer<render::EntityRenderer>(m_Camera, clientWorld);
+			m_Renderer.AddRenderer<render::TowerRenderer>(m_Camera, clientWorld);
+
+			auto& list = m_Renderer.AddRenderer<render::PlayerListRenderer>(m_Client->GetPlayers());
+
+			list.OnPlayerCreate.Connect([this]() {
+				auto newSocket = client::FakeSocket::Connect(m_ServerSocket);
+				auto newClient = std::make_unique<client::Client>(newSocket);
+				newClient->ChangeState<client::LoggingState>("Bot");
+				m_FakeClients.push_back(std::move(newClient));
+			});
+
+			list.OnPlayerKick.Connect([this](PlayerID a_Player) {
+				auto it = std::find_if(m_FakeClients.begin(), m_FakeClients.end(), [a_Player](auto& clientPtr){
+					if (!clientPtr->GetId().has_value())
+						return false;
+					return clientPtr->GetId().value() == a_Player;
+				});
+				m_FakeClients.erase(it);
+			});
+
+			// update state
+			m_ClientState = gameState;
+		}
+	});
+
+	m_Client->ChangeState<client::LoggingState>("Player0");
+
+	// camera
+	m_Camera.SetCamPos({77, 7, 13});
+	m_Camera.UpdatePerspective(m_StateMachine.GetAspectRatio());
+}
+
+void DebugWorldState::Update(float a_Delta) {
+	m_Server->Update(a_Delta);
+	m_Client->Update(a_Delta);
+	if (m_ClientState)
+		m_Renderer.Render(m_ClientState->GetCurrentLerp());
+}
+
+void DebugWorldState::OnAspectRatioChange(float a_Ratio) {
+	m_Camera.UpdatePerspective(a_Ratio);
+}
+
+void DebugWorldState::OnKeyDown(SDL_Keycode a_Key) {
+	// temporary tests
+	switch (a_Key) {
+		case SDLK_A:
+			m_Client->SendPacket(td::protocol::packets::SpawnTroopPacket(td::EntityType::Zombie, 1));
+			break;
+
+		case SDLK_Z:
+			m_Client->SendPacket(td::protocol::packets::PlaceTowerPacket(td::TowerType::Archer, td::TowerCoords(77, 13)));
+			break;
+
+		default:
+			break;
+	}
+}
+
+DebugWorldState::~DebugWorldState() {}
+
+}  // namespace td

src/td/display/state/MainMenuState.cpp

@@ -0,0 +1,42 @@
+#include <td/display/state/MainMenuState.h>
+
+#include <imgui.h>
+#include <td/display/menu/MainMenu.h>
+#include <td/display/state/DebugWorldState.h>
+
+namespace td {
+
+MainMenuState::MainMenuState(Display& a_Display) : DisplayState(a_Display) {
+	PushState<MainMenu>();
+}
+
+MainMenuState::~MainMenuState() {}
+
+static int GetWindowFullScreenFlags() {
+	return ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoBackground;
+}
+
+static void SetNextWindowFullScreen() {
+	const ImGuiViewport* viewport = ImGui::GetMainViewport();
+	ImGui::SetNextWindowPos(viewport->WorkPos);
+	ImGui::SetNextWindowSize(viewport->WorkSize);
+}
+
+void MainMenuState::Update(float a_Delta) {
+	SetNextWindowFullScreen();
+	ImGui::Begin("MainWindow", nullptr, GetWindowFullScreenFlags());
+	MainMenuStateStack::Update();
+	ImGui::End();
+}
+
+void MainMenuState::RenderBackButton() {
+	if (ImGui::Button("Back"))
+		PopState();
+}
+
+void MainMenuState::OnKeyDown(SDL_Keycode a_Key) {
+	if (a_Key == SDLK_ESCAPE)
+		PopState();
+}
+
+}  // namespace td

src/td/game/GameHistory.cpp

@@ -1,44 +0,0 @@
-#include <td/game/GameHistory.h>
-
-namespace td {
-namespace game {
-
-GameHistory::GameHistory() : m_History(std::numeric_limits<HistorySizeType>::max()), m_Cursor(0) {}
-
-void GameHistory::SetLockStep(HistorySizeType a_Index, protocol::LockStep&& a_LockStep) {
-	m_History[a_Index] = std::move(a_LockStep);
-}
-
-const protocol::LockStep& GameHistory::GetLockStep(HistorySizeType a_Index) const {
-	return *m_History[a_Index];
-}
-
-bool GameHistory::HasLockStep(HistorySizeType a_Index) const {
-	return m_History[a_Index].has_value();
-}
-
-const protocol::LockStep& GameHistory::GetNextStep() {
-	return GetLockStep(m_Cursor++);
-}
-
-bool GameHistory::HasNextStep() const {
-	return HasLockStep(m_Cursor);
-}
-
-void GameHistory::FromPacket(td::protocol::pdata::LockSteps&& a_Steps) {
-	for (int i = 0; i < LOCKSTEP_BUFFER_SIZE; i++) {
-		protocol::LockStep& step = a_Steps.m_LockSteps[i];
-		SetLockStep(i + a_Steps.m_FirstFrameNumber, std::move(step));
-	}
-}
-
-td::protocol::packets::LockStepsPacket GameHistory::ToPacket(HistorySizeType a_StartIndex) {
-	Array<protocol::LockStep, LOCKSTEP_BUFFER_SIZE> steps;
-	for (int i = 0; i < LOCKSTEP_BUFFER_SIZE; i++) {
-		steps[i] = GetLockStep(a_StartIndex + i);
-	}
-	return {a_StartIndex, std::move(steps)};
-}
-
-}  // namespace game
-}  // namespace td

src/td/game/World.cpp

@@ -1,31 +1,44 @@
 #include <td/game/World.h>
 
+#include <td/simulation/WorldTicker.h>
+#include <td/protocol/packet/PacketSerialize.h>
+
 namespace td {
 namespace game {
 
-World::World() : m_Teams{Team{TeamColor::Red}, Team{TeamColor::Blue}} {
+class ColorTileVisitor : public TileHandler {
+  private:
+	const World& m_World;
+	const Color* m_Result;
 
+  public:
+	ColorTileVisitor(const World& a_World) : m_World(a_World), m_Result(nullptr) {}
+
+	virtual void Handle(const EmptyTile& a_Tile) override {}
+
+	virtual void Handle(const TowerTile& a_Tile) override {
+		m_Result = &m_World.GetTowerTileColorPalette()[a_Tile->m_ColorPaletteRef];
 	}
 
-const Color* World::GetTileColor(TilePtr tile) const {
-	switch (tile->GetType()) {
-		case TileType::Tower: {
-			TowerTile* towerTile = dynamic_cast<TowerTile*>(tile.get());
-			return &m_TowerPlacePalette[towerTile->color_palette_ref];
+	virtual void Handle(const WalkableTile& a_Tile) override {
+		m_Result = &m_World.GetWalkableTileColor();
 	}
-		case TileType::Walk: {
-			return &m_WalkablePalette;
+
+	virtual void Handle(const DecorationTile& a_Tile) override {
+		m_Result = &m_World.GetDecorationPalette()[a_Tile->m_ColorPaletteRef];
 	}
-		case TileType::Decoration: {
-			DecorationTile* towerTile = dynamic_cast<DecorationTile*>(tile.get());
-			return &m_DecorationPalette[towerTile->color_palette_ref];
-			break;
+
+	const Color* GetResult() {
+		return m_Result;
 	}
-		default: {
-			return nullptr;
-		}
-	}
-	return nullptr;
+};
+
+World::World() : m_CurrentState(std::make_shared<sim::WorldSnapshot>()), m_NextState(m_CurrentState) {}
+
+const Color* World::GetTileColor(const TilePtr& tile) const {
+	ColorTileVisitor visitor(*this);
+	tile->Dispatch(visitor);
+	return visitor.GetResult();
 }
 
 bool World::LoadMap(const protocol::pdata::WorldHeader& a_WorldHeader) {
@@ -40,20 +53,41 @@ bool World::LoadMap(const protocol::pdata::WorldHeader& a_WorldHeader) {
 	m_SpawnColorPalette = a_WorldHeader.m_SpawnColorPalette;
 
 	GetRedTeam().GetCastle() = a_WorldHeader.m_RedCastle;
-	GetRedTeam().GetCastle().SetTeam(&GetRedTeam());
+	// GetRedTeam().GetCastle().SetTeam(&GetRedTeam());
 
 	GetBlueTeam().GetCastle() = a_WorldHeader.m_BlueCastle;
-	GetBlueTeam().GetCastle().SetTeam(&GetBlueTeam());
+	// GetBlueTeam().GetCastle().SetTeam(&GetBlueTeam());
 
 	m_TilePalette = a_WorldHeader.m_TilePalette;
 
 	return true;
 }
 
+protocol::packets::WorldHeaderPacket World::GetPacketHeader() const {
+	return protocol::packets::WorldHeaderPacket(m_TowerPlacePalette, m_WalkablePalette, m_DecorationPalette, m_Background,
+		m_SpawnColorPalette, m_TilePalette, GetRedTeam().GetSpawn(), GetBlueTeam().GetSpawn(), GetRedTeam().GetCastle(),
+		GetBlueTeam().GetCastle());
+}
+
+protocol::packets::WorldDataPacket World::GetPacketData() const {
+	return protocol::packets::WorldDataPacket(m_Chunks);
+}
+
 bool World::LoadMap(const protocol::pdata::WorldData& a_WorldData) {
 	m_Chunks = a_WorldData.m_Chunks;
 	return true;
 }
 
+const std::shared_ptr<sim::WorldSnapshot>& World::Tick(const protocol::LockStep& a_LockStep, FpFloat a_Delta) {
+	m_CurrentState = m_NextState;
+	m_NextState = std::make_shared<sim::WorldSnapshot>(m_Ticker.NextStep(*this, *m_NextState, a_LockStep, a_Delta));
+	return m_CurrentState;
+}
+
+void World::ResetSnapshots(std::shared_ptr<sim::WorldSnapshot>& a_Current, std::shared_ptr<sim::WorldSnapshot>& a_Next) {
+	m_CurrentState = a_Current;
+	m_NextState = a_Next;
+}
+
 }  // namespace game
 }  // namespace td

src/td/game/WorldTypes.cpp

@@ -0,0 +1,37 @@
+#include <td/game/WorldTypes.h>
+
+namespace td {
+namespace game {
+
+const int BITS_IN_BYTE = 8;
+const int BITS_IN_LONG = BITS_IN_BYTE * sizeof(std::uint64_t);
+
+static unsigned int countBits(unsigned int number) {
+	// log function in base 2
+	// take only integer part
+	return static_cast<unsigned int>(std::log2(number) + 1);
+}
+
+TileIndex Chunk::GetTileIndex(std::uint16_t tileNumber) const {
+	const std::uint8_t bitsPerTile = countBits(m_Palette.size());
+
+	const std::size_t startLong = (tileNumber * bitsPerTile) / BITS_IN_LONG;
+	const std::size_t startOffset = (tileNumber * bitsPerTile) % BITS_IN_LONG;
+	const std::size_t endLong = ((tileNumber + 1) * bitsPerTile - 1) / BITS_IN_LONG;
+
+	const Chunk::ChunkData::value_type individualValueMask = ((1 << bitsPerTile) - 1);
+
+	td::game::Chunk::ChunkData::value_type value;
+	if (startLong == endLong) {
+		value = (m_Data[startLong] >> startOffset);
+	} else {
+		int endOffset = BITS_IN_LONG - startOffset;
+		value = (m_Data[startLong] >> startOffset | m_Data[endLong] << endOffset);
+	}
+	value &= individualValueMask;
+
+	return m_Palette.at(value);
+}
+
+}  // namespace game
+}  // namespace td

src/td/protocol/packet/ChunkSerialize.cpp

@@ -0,0 +1,9 @@
+#include <td/protocol/packet/PacketSerialize.h>
+
+namespace td {
+namespace game {
+
+
+
+} // namespace game
+} // namespace td

src/td/protocol/packet/PacketSerialize.cpp

@@ -0,0 +1,33 @@
+#include <td/protocol/packet/PacketData.h>
+#include <td/protocol/packet/PacketSerialize.h>
+
+#include <sp/common/DataBufferOperators.h>
+
+namespace td {
+namespace game {
+
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const TeamCastle& a_Castle) {
+	return a_Buffer << a_Castle.GetCenterX() << a_Castle.GetCenterY();
+}
+
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, TeamCastle& a_Castle) {
+	float x, y;
+	a_Buffer >> x >> y;
+	a_Castle.SetCenter({x, y});
+	return a_Buffer;
+}
+
+sp::DataBuffer& operator<<(sp::DataBuffer& a_Buffer, const Spawn& a_Spawn) {
+	return a_Buffer << a_Spawn.GetCenterX() << a_Spawn.GetCenterY();
+}
+
+sp::DataBuffer& operator>>(sp::DataBuffer& a_Buffer, Spawn& a_Spawn) {
+	float x, y;
+	a_Buffer >> x >> y;
+	a_Spawn.SetCenter({x, y});
+	return a_Buffer;
+}
+
+
+}  // namespace game
+}  // namespace td