diff --git a/include/td/game/Team.h b/include/td/game/Team.h
index a73fb76..70cbd20 100644
--- a/include/td/game/Team.h
+++ b/include/td/game/Team.h
@@ -80,7 +80,29 @@ 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::Red}, Team{TeamColor::Blue}}{
+		
+	}
+
+	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
diff --git a/include/td/game/Towers.h b/include/td/game/Towers.h
index 4715855..574c1d2 100644
--- a/include/td/game/Towers.h
+++ b/include/td/game/Towers.h
@@ -107,15 +107,15 @@ class ConcreteTower : public sp::ConcreteMessage<TowerData, Tower, Type, false>
   public:
 	using HandlerType = typename sp::ConcreteMessage<TowerData, Tower, Type, false>::HandlerType;
 
-	virtual TowerSize GetSize() const {
+	virtual TowerSize GetSize() const override {
 		return Size;
 	}
 
-	virtual TowerType GetType() const {
+	virtual TowerType GetType() const override {
 		return Type;
 	}
 
-	virtual void Tick(std::uint64_t delta, World* world) {}
+	virtual void Tick(std::uint64_t delta, World* world) override {}
 
 	virtual void Dispatch(HandlerType& handler) const override {
 		handler.Handle(*this);
diff --git a/include/td/game/World.h b/include/td/game/World.h
index 5c591bd..f03f5cf 100644
--- a/include/td/game/World.h
+++ b/include/td/game/World.h
@@ -20,8 +20,8 @@ class World {
 
 	TilePalette m_TilePalette;
 
-	sim::WorldSnapshot m_CurrentState;
-	sim::WorldSnapshot m_NextState;
+	std::shared_ptr<sim::WorldSnapshot> m_CurrentState;
+	std::shared_ptr<sim::WorldSnapshot> m_NextState;
 
   private:
 	sim::WorldTicker m_Ticker;
@@ -82,52 +82,55 @@ class World {
 	}
 
 	const MobList& GetMobList() const {
-		return m_CurrentState.m_Mobs;
+		return m_CurrentState->m_Mobs;
 	}
 	MobList& GetMobList() {
-		return m_CurrentState.m_Mobs;
+		return m_CurrentState->m_Mobs;
 	}
 
 	const Color* GetTileColor(const TilePtr& tile) const;
 
 	Team& GetRedTeam() {
-		return m_CurrentState.m_Teams[static_cast<std::uint8_t>(TeamColor::Red)];
+		return m_CurrentState->m_Teams[TeamColor::Red];
 	}
 	const Team& GetRedTeam() const {
-		return m_CurrentState.m_Teams[static_cast<std::uint8_t>(TeamColor::Red)];
+		return m_CurrentState->m_Teams[TeamColor::Red];
 	}
 
 	Team& GetBlueTeam() {
-		return m_CurrentState.m_Teams[static_cast<std::uint8_t>(TeamColor::Blue)];
+		return m_CurrentState->m_Teams[TeamColor::Blue];
 	}
 	const Team& GetBlueTeam() const {
-		return m_CurrentState.m_Teams[static_cast<std::uint8_t>(TeamColor::Red)];
+		return m_CurrentState->m_Teams[TeamColor::Red];
 	}
 
 	Team& GetTeam(TeamColor team) {
-		return m_CurrentState.m_Teams[static_cast<std::uint8_t>(team)];
+		return m_CurrentState->m_Teams[team];
 	}
 	const Team& GetTeam(TeamColor team) const {
-		return m_CurrentState.m_Teams[static_cast<std::uint8_t>(team)];
+		return m_CurrentState->m_Teams[team];
 	}
 
 	const TeamList& GetTeams() const {
-		return m_CurrentState.m_Teams;
+		return m_CurrentState->m_Teams;
 	}
 
 	const TowerList& GetTowers() const {
-		return m_CurrentState.m_Towers;
+		return m_CurrentState->m_Towers;
 	}
 
 	TowerPtr GetTowerById(TowerID tower);
 
 	const Player* GetPlayerById(PlayerID id) const;
 
-	void Tick(const protocol::LockStep& a_LockStep, FpFloat a_Delta);
+	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();
+
 };
 
 
diff --git a/include/td/input/Display.h b/include/td/input/Display.h
index cb4c6c1..7d1bf87 100644
--- a/include/td/input/Display.h
+++ b/include/td/input/Display.h
@@ -3,6 +3,7 @@
 #include <string>
 
 #include <SDL3/SDL_video.h>
+#include <SDL3/SDL_keycode.h>
 #include <td/misc/Signal.h>
 
 namespace td {
@@ -10,6 +11,7 @@ namespace td {
 class Display {
   public:
 	utils::Signal<float> OnAspectRatioChange;
+	utils::Signal<SDL_Keycode> OnKeyDown;
 
 	Display(int a_Width, int a_Height, const std::string& a_Title);
 	~Display();
diff --git a/include/td/protocol/packet/PacketData.h b/include/td/protocol/packet/PacketData.h
index 32b954a..d395ec3 100644
--- a/include/td/protocol/packet/PacketData.h
+++ b/include/td/protocol/packet/PacketData.h
@@ -74,7 +74,7 @@ struct BeginGame {
 
 struct LockSteps {
 	std::uint16_t m_FirstFrameNumber;
-	Array<LockStep, LOCKSTEP_BUFFER_SIZE> m_LockSteps;
+	std::array<LockStep, LOCKSTEP_BUFFER_SIZE> m_LockSteps;
 };
 
 struct WorldHeader {
diff --git a/include/td/simulation/RealTimeSimulation.h b/include/td/simulation/RealTimeSimulation.h
index 694f500..2fe4db2 100644
--- a/include/td/simulation/RealTimeSimulation.h
+++ b/include/td/simulation/RealTimeSimulation.h
@@ -1,34 +1,61 @@
 #pragma once
 
 #include <td/game/World.h>
+#include <optional>
 
 namespace td {
 namespace sim {
 
 using GameHistory = std::vector<td::protocol::LockStep>;
+using GameBuffer = std::vector<std::optional<td::protocol::LockStep>>;
 
 class RealTimeSimulation {
   private:
 	std::uint64_t m_StepTime;
 	game::World& m_World;
-	GameHistory m_History;
+	GameBuffer m_History;
 	std::uint64_t m_CurrentTime;
 	std::uint64_t m_LastTime;
 	std::size_t m_CurrentStep;
 
+	std::shared_ptr<WorldSnapshot> m_LastSnapshot;
+	std::uint64_t m_LastValidStep;
+
+	static const protocol::LockStep EMPTY_LOCKSTEP;
+
   public:
 	/**
+	 * \brief Replay constructor
 	 * \param a_StepTime in ms
 	 */
-	RealTimeSimulation(game::World& a_World, GameHistory&& a_History, std::uint64_t a_StepTime);
+	RealTimeSimulation(game::World& a_World, const GameHistory& a_History, std::uint64_t a_StepTime);
+
+	/**
+	 * \brief Live update constructor (continuous game updates)
+	 * \param a_StepTime in ms
+	 */
+	RealTimeSimulation(game::World& a_World, std::uint64_t a_StepTime);
 
 	/**
 	 * \return the progress [0-1] between two steps
 	 */
 	float Update();
 
+	void HandlePacket(const protocol::packets::LockStepsPacket& a_LockSteps);
+	void HandlePacket(const protocol::packets::PredictCommandPacket& a_Predict);
+
   private:
 	void Step();
+
+	/**
+	 * \brief Ticks a_Count times
+	 */
+	void FastForward(std::size_t a_Count);
+
+	/**
+	 * \brief Tries to recompute simulation if needed (for example in late command receival)
+	 */
+	void FastReplay();
 };
 
 }  // namespace sim
diff --git a/src/main.cpp b/src/main.cpp
index 6e3140b..08a570a 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -103,7 +103,17 @@ int main(int argc, char** argv) {
 	cam.SetCamPos({77, 5, 13});
 	cam.UpdatePerspective(display.GetAspectRatio());
 
-	td::sim::RealTimeSimulation simulation(w, std::move(gh), 500);
+	td::sim::RealTimeSimulation simulation(w, 500);
+
+	display.OnKeyDown.Connect([&simulation](SDL_Keycode key){
+		if (key == SDLK_A) {
+			auto spawn = std::make_shared<td::protocol::commands::SpawnTroopCommand>(0, 0, td::Vec2fp{td::FpFloat(77), td::FpFloat(13)}, 0);
+			std::array<td::protocol::LockStep, LOCKSTEP_BUFFER_SIZE> steps{};
+			steps[0].push_back(spawn);
+			td::protocol::packets::LockStepsPacket packet{0, steps};
+			simulation.HandlePacket(packet);
+		}
+	});
 
 	while (!display.IsCloseRequested()) {
 		display.PollEvents();
diff --git a/src/td/game/World.cpp b/src/td/game/World.cpp
index b4c0afc..840eb59 100644
--- a/src/td/game/World.cpp
+++ b/src/td/game/World.cpp
@@ -5,7 +5,7 @@
 namespace td {
 namespace game {
 
-World::World() : m_CurrentState{.m_Teams{Team{TeamColor::Red}, Team{TeamColor::Blue}}}, m_NextState{.m_Teams{Team{TeamColor::Red}, Team{TeamColor::Blue}}} {}
+World::World() : m_CurrentState(std::make_shared<sim::WorldSnapshot>()), m_NextState(m_CurrentState) {}
 
 const Color* World::GetTileColor(const TilePtr& tile) const {
 	switch (tile->GetType()) {
@@ -55,9 +55,15 @@ bool World::LoadMap(const protocol::pdata::WorldData& a_WorldData) {
 	return true;
 }
 
-void World::Tick(const protocol::LockStep& a_LockStep, FpFloat a_Delta) {
+const std::shared_ptr<sim::WorldSnapshot>& World::Tick(const protocol::LockStep& a_LockStep, FpFloat a_Delta) {
 	m_CurrentState = m_NextState;
-	m_NextState = m_Ticker.NextStep(*this, m_NextState, a_LockStep, a_Delta);
+	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
diff --git a/src/td/input/Display.cpp b/src/td/input/Display.cpp
index 0536daf..d744d10 100644
--- a/src/td/input/Display.cpp
+++ b/src/td/input/Display.cpp
@@ -119,6 +119,7 @@ void Display::PollEvents() {
 			case SDL_EVENT_QUIT:
 			case SDL_EVENT_WINDOW_CLOSE_REQUESTED: {
 				m_ShouldClose = true;
+				break;
 			}
 
 			case SDL_EVENT_WINDOW_RESIZED: {
@@ -126,6 +127,13 @@ void Display::PollEvents() {
 				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:
diff --git a/src/td/simulation/CommandApply.cpp b/src/td/simulation/CommandApply.cpp
index dd227af..8e17aef 100644
--- a/src/td/simulation/CommandApply.cpp
+++ b/src/td/simulation/CommandApply.cpp
@@ -5,7 +5,9 @@ namespace sim {
 
 CommandApply::CommandApply(const game::World& a_World, WorldSnapshot& a_Snapshot) : m_World(a_World), m_Snapshot(a_Snapshot) {}
 
-void CommandApply::Handle(const protocol::commands::EndCommand& a_End) {}
+void CommandApply::Handle(const protocol::commands::EndCommand& a_End) {
+	(void) m_World;
+}
 
 void CommandApply::Handle(const protocol::commands::PlaceTowerCommand& a_PlaceTower) {
 	static game::TowerFactory factory;
diff --git a/src/td/simulation/GameHistory.cpp b/src/td/simulation/GameHistory.cpp
index a707db0..0639723 100644
--- a/src/td/simulation/GameHistory.cpp
+++ b/src/td/simulation/GameHistory.cpp
@@ -33,7 +33,7 @@ void GameHistory::FromPacket(td::protocol::pdata::LockSteps&& a_Steps) {
 }
 
 td::protocol::packets::LockStepsPacket GameHistory::ToPacket(HistorySizeType a_StartIndex) {
-	Array<protocol::LockStep, LOCKSTEP_BUFFER_SIZE> steps;
+	std::array<protocol::LockStep, LOCKSTEP_BUFFER_SIZE> steps;
 	for (int i = 0; i < LOCKSTEP_BUFFER_SIZE; i++) {
 		steps[i] = GetLockStep(a_StartIndex + i);
 	}
diff --git a/src/td/simulation/RealTimeSimulation.cpp b/src/td/simulation/RealTimeSimulation.cpp
index 438c424..26ec283 100644
--- a/src/td/simulation/RealTimeSimulation.cpp
+++ b/src/td/simulation/RealTimeSimulation.cpp
@@ -5,18 +5,37 @@
 namespace td {
 namespace sim {
 
+const protocol::LockStep RealTimeSimulation::EMPTY_LOCKSTEP;
+
 std::uint64_t GetTime() {
 	return static_cast<std::uint64_t>(
 		std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock().now().time_since_epoch()).count());
 }
 
-RealTimeSimulation::RealTimeSimulation(game::World& a_World, GameHistory&& a_History, std::uint64_t a_StepTime) :
+RealTimeSimulation::RealTimeSimulation(game::World& a_World, const GameHistory& a_History, std::uint64_t a_StepTime) :
 	m_StepTime(a_StepTime),
 	m_World(a_World),
-	m_History(std::move(a_History)),
 	m_CurrentTime(0),
 	m_LastTime(GetTime()),
-	m_CurrentStep(0) {
+	m_CurrentStep(0),
+	m_LastSnapshot(std::make_shared<WorldSnapshot>()),
+	m_LastValidStep(0) {
+	m_History.reserve(a_History.size());
+	for (const auto& lockstep : a_History) {
+		m_History.emplace_back(lockstep);
+	}
+	Step();
+}
+
+RealTimeSimulation::RealTimeSimulation(game::World& a_World, std::uint64_t a_StepTime) :
+	m_StepTime(a_StepTime),
+	m_World(a_World),
+	m_History(std::numeric_limits<std::uint16_t>::max()),
+	m_CurrentTime(0),
+	m_LastTime(GetTime()),
+	m_CurrentStep(0),
+	m_LastSnapshot(std::make_shared<WorldSnapshot>()),
+	m_LastValidStep(0) {
 	Step();
 }
 
@@ -28,13 +47,47 @@ float RealTimeSimulation::Update() {
 		Step();
 		m_CurrentTime -= m_StepTime;
 	}
-	return (float) m_CurrentTime / (float) m_StepTime;
+	return (float)m_CurrentTime / (float)m_StepTime;
 }
 
 void RealTimeSimulation::Step() {
-	m_World.Tick(m_History[m_CurrentStep], FpFloat(m_StepTime) / FpFloat(1000));
+	const auto& step = m_History[m_CurrentStep];
+	if (step.has_value()) {
+		m_LastSnapshot = m_World.Tick(step.value(), FpFloat(m_StepTime) / FpFloat(1000));
+		m_LastValidStep = m_CurrentStep;
+	} else {
+		m_World.Tick(EMPTY_LOCKSTEP, FpFloat(m_StepTime) / FpFloat(1000));
+	}
 	m_CurrentStep++;
 }
 
+void RealTimeSimulation::HandlePacket(const protocol::packets::LockStepsPacket& a_LockSteps) {
+	const auto& steps = a_LockSteps->m_LockSteps;
+	for (std::size_t i = 0; i < LOCKSTEP_BUFFER_SIZE; i++) {
+		m_History[a_LockSteps->m_FirstFrameNumber + i] = steps[i];
+	}
+	FastReplay();
+}
+
+void RealTimeSimulation::HandlePacket(const protocol::packets::PredictCommandPacket& a_Predict) {}
+
+void RealTimeSimulation::FastForward(std::size_t a_Count) {
+	for (std::size_t i = 0; i < a_Count; i++) {
+		Step();
+	}
+}
+
+void RealTimeSimulation::FastReplay() {
+	if (m_LastValidStep >= m_CurrentStep)
+		return;
+
+	m_World.ResetSnapshots(m_LastSnapshot, m_LastSnapshot);
+
+	const std::size_t stepCount = m_CurrentStep - m_LastValidStep;
+	m_CurrentStep = m_LastValidStep;
+	
+	FastForward(stepCount);
+}
+
 }  // namespace sim
 }  // namespace td