diff --git a/game/sim/audio.py b/game/sim/audio.py
new file mode 100644
index 0000000..6c0dc67
--- /dev/null
+++ b/game/sim/audio.py
@@ -0,0 +1,36 @@
+class SoundEvent:
+    __slots__ = ("name", "x", "frame")
+
+    def __init__(self, name, x, frame):
+        self.name = name
+        self.x = x
+        self.frame = frame
+
+
+class AudioBus:
+    def __init__(self, sink=None, historyCap=64):
+        self.sink = sink
+        self.events = []
+        self.historyCap = historyCap
+        self.frame = 0
+        self.totalEmitted = 0
+
+    def setSink(self, sink):
+        self.sink = sink
+
+    def tick(self):
+        self.frame += 1
+
+    def play(self, name, x=None):
+        event = SoundEvent(name, x, self.frame)
+        self.events.append(event)
+        if len(self.events) > self.historyCap:
+            self.events.pop(0)
+        self.totalEmitted += 1
+        if self.sink is not None:
+            self.sink(event)
+
+    def drain(self):
+        drained = self.events
+        self.events = []
+        return drained
diff --git a/game/sim/gameState.py b/game/sim/gameState.py
new file mode 100644
index 0000000..2746d07
--- /dev/null
+++ b/game/sim/gameState.py
@@ -0,0 +1,78 @@
+from .world import World
+
+MENU = "menu"
+PLAYING = "playing"
+PAUSED = "paused"
+GAMEOVER = "gameover"
+COMPLETE = "complete"
+VICTORY = "victory"
+
+
+class Game:
+    def __init__(self, levels, rng=None):
+        self.levels = list(levels)
+        self.levelIndex = 0
+        self.mode = MENU
+        self.world = None
+        self.rng = rng
+        self.frame = 0
+        self.transitions = []
+
+    def startLevel(self, index):
+        self.levelIndex = index
+        self.world = World(self.levels[index], rng=self.rng)
+        self.setMode(PLAYING)
+
+    def start(self):
+        self.startLevel(0)
+
+    def setMode(self, mode):
+        if mode != self.mode:
+            self.transitions.append((self.mode, mode, self.frame))
+        self.mode = mode
+
+    def update(self, command):
+        self.frame += 1
+        handler = {
+            MENU: self.updateMenu,
+            PLAYING: self.updatePlaying,
+            PAUSED: self.updatePaused,
+            GAMEOVER: self.updateGameover,
+            COMPLETE: self.updateComplete,
+            VICTORY: self.updateVictory,
+        }[self.mode]
+        handler(command)
+
+    def updateMenu(self, command):
+        if command.confirm or command.jump:
+            self.start()
+
+    def updatePlaying(self, command):
+        if command.pause:
+            self.setMode(PAUSED)
+            return
+        self.world.step(command)
+        if self.world.gameOver:
+            self.setMode(GAMEOVER)
+        elif self.world.completed:
+            if self.levelIndex + 1 < len(self.levels):
+                self.setMode(COMPLETE)
+            else:
+                self.setMode(VICTORY)
+
+    def updatePaused(self, command):
+        if command.pause:
+            self.setMode(PLAYING)
+
+    def updateGameover(self, command):
+        if command.confirm:
+            self.setMode(MENU)
+
+    def updateComplete(self, command):
+        if command.confirm:
+            self.startLevel(self.levelIndex + 1)
+
+    def updateVictory(self, command):
+        if command.confirm:
+            self.levelIndex = 0
+            self.setMode(MENU)
diff --git a/game/sim/stateMachine.py b/game/sim/stateMachine.py
new file mode 100644
index 0000000..e4d04a4
--- /dev/null
+++ b/game/sim/stateMachine.py
@@ -0,0 +1,50 @@
+class State:
+    name = "state"
+
+    def onEnter(self, owner, world):
+        pass
+
+    def onExit(self, owner, world):
+        pass
+
+    def update(self, owner, world):
+        return None
+
+
+class StateMachine:
+    def __init__(self, owner):
+        self.owner = owner
+        self.states = {}
+        self.current = None
+        self.previous = None
+        self.timeInState = 0
+
+    def addState(self, state):
+        self.states[state.name] = state
+        return self
+
+    def setInitial(self, name, world=None):
+        self.current = self.states[name]
+        self.timeInState = 0
+        if world is not None:
+            self.current.onEnter(self.owner, world)
+        return self
+
+    def transition(self, name, world):
+        if name == self.current.name:
+            return
+        self.previous = self.current
+        self.current.onExit(self.owner, world)
+        self.current = self.states[name]
+        self.timeInState = 0
+        self.current.onEnter(self.owner, world)
+
+    def update(self, world):
+        self.timeInState += 1
+        nextState = self.current.update(self.owner, world)
+        if nextState is not None and nextState != self.current.name:
+            self.transition(nextState, world)
+
+    @property
+    def stateName(self):
+        return self.current.name if self.current else None