diff --git a/game/sim/enemies.py b/game/sim/enemies.py
new file mode 100644
index 0000000..e60f9ea
--- /dev/null
+++ b/game/sim/enemies.py
@@ -0,0 +1,269 @@
+import math
+
+from .. import constants
+from ..constants import tileSize
+from .entity import Actor
+from . import physics
+from .stateMachine import State, StateMachine
+from .projectile import Projectile
+
+
+class Enemy(Actor):
+    stompable = True
+    hasGravity = True
+    contactDamage = constants.contactDamage
+    kind = "enemy"
+
+    def __init__(self, x, y, w, h):
+        super().__init__(x, y, w, h)
+        self.hp = 1
+        self.direction = -1
+        self.machine = StateMachine(self)
+        self.spawnX = float(x)
+        self.spawnY = float(y)
+
+    def initialState(self):
+        return None
+
+    def stepGround(self, world, speed):
+        self.vx = speed * self.direction
+        self.vy += constants.gravity
+        if self.vy > constants.maxFallSpeed:
+            self.vy = constants.maxFallSpeed
+        physics.moveHorizontal(self, world.level, world.platforms)
+        if (self.direction > 0 and self.onWallRight) or (self.direction < 0 and self.onWallLeft):
+            self.direction *= -1
+            self.vx = 0.0
+        wasOnGround = self.onGround
+        physics.moveVertical(self, world.level, world.platforms)
+        physics.resolveSlope(self, world.level, wasOnGround)
+        self.facing = self.direction
+        if self.onGround:
+            aheadX = self.x + (self.w + 1 if self.direction > 0 else -1)
+            col = int(aheadX // tileSize)
+            row = int((self.y + self.h + 2) // tileSize)
+            if not world.level.solidAt(col, row) and not world.level.oneWayAt(col, row) and not world.level.slopeAt(col, row):
+                self.direction *= -1
+
+    def playerDistance(self, world):
+        return abs(world.player.centerX - self.centerX)
+
+    def playerVerticalDistance(self, world):
+        return abs(world.player.centerY - self.centerY)
+
+    def facePlayer(self, world):
+        self.direction = 1 if world.player.centerX >= self.centerX else -1
+
+    def update(self, world):
+        if self.machine.current is None:
+            self.machine.setInitial(self.initialState(), world)
+        self.machine.update(world)
+
+    def onStomped(self, world):
+        self.hp -= 1
+        if self.hp <= 0:
+            self.alive = False
+        world.spawnBurst("stomp", self.centerX, self.centerY, 6)
+
+
+class PatrolState(State):
+    name = "patrol"
+
+    def update(self, owner, world):
+        owner.stepGround(world, constants.enemySpeed)
+        return None
+
+
+class Goomba(Enemy):
+    kind = "goomba"
+
+    def initialState(self):
+        return "patrol"
+
+    def __init__(self, x, y):
+        super().__init__(x, y, 16, 16)
+        self.machine.addState(PatrolState())
+
+
+class ChaserPatrol(State):
+    name = "patrol"
+    detectRange = 90.0
+    detectHeight = 40.0
+
+    def update(self, owner, world):
+        owner.stepGround(world, constants.enemySpeed)
+        if owner.playerDistance(world) < self.detectRange and owner.playerVerticalDistance(world) < self.detectHeight:
+            return "chase"
+        return None
+
+
+class ChaseState(State):
+    name = "chase"
+    loseRange = 160.0
+
+    def onEnter(self, owner, world):
+        world.spawnBurst("alert", owner.centerX, owner.top - 4, 3)
+
+    def update(self, owner, world):
+        owner.facePlayer(world)
+        owner.stepGround(world, constants.chaserSpeed)
+        if owner.playerDistance(world) > self.loseRange:
+            return "patrol"
+        return None
+
+
+class Chaser(Enemy):
+    kind = "chaser"
+
+    def __init__(self, x, y):
+        super().__init__(x, y, 16, 16)
+        self.hp = 2
+        self.machine.addState(ChaserPatrol()).addState(ChaseState())
+
+    def initialState(self):
+        return "patrol"
+
+
+class FlyerHover(State):
+    name = "hover"
+    detectRange = 120.0
+
+    def update(self, owner, world):
+        owner.hoverPhase += 0.08
+        owner.x += owner.direction * constants.flyerSpeed
+        owner.y = owner.baseY + math.sin(owner.hoverPhase) * 14.0
+        box = owner.aabb
+        blockedRight = owner.direction > 0 and physics.touchingSolidSide(owner, world.level, world.platforms, 1)
+        blockedLeft = owner.direction < 0 and physics.touchingSolidSide(owner, world.level, world.platforms, -1)
+        if blockedRight or blockedLeft or owner.x < owner.patrolMin or owner.x > owner.patrolMax:
+            owner.direction *= -1
+            owner.x = min(max(owner.x, owner.patrolMin), owner.patrolMax)
+        owner.facing = owner.direction
+        if owner.playerDistance(world) < self.detectRange:
+            return "pursue"
+        return None
+
+
+class FlyerPursue(State):
+    name = "pursue"
+    loseRange = 190.0
+
+    def update(self, owner, world):
+        target = world.player
+        dx = target.centerX - owner.centerX
+        dy = target.centerY - owner.centerY
+        distance = math.hypot(dx, dy) or 1.0
+        owner.x += (dx / distance) * constants.flyerSpeed * 1.4
+        owner.y += (dy / distance) * constants.flyerSpeed * 1.4
+        owner.baseY = owner.y
+        owner.facing = 1 if dx >= 0 else -1
+        owner.direction = owner.facing
+        if owner.playerDistance(world) > self.loseRange:
+            return "hover"
+        return None
+
+
+class Flyer(Enemy):
+    kind = "flyer"
+    hasGravity = False
+    stompable = True
+
+    def __init__(self, x, y):
+        super().__init__(x, y, 16, 14)
+        self.baseY = float(y)
+        self.hoverPhase = 0.0
+        self.patrolMin = float(x) - 48.0
+        self.patrolMax = float(x) + 48.0
+        self.machine.addState(FlyerHover()).addState(FlyerPursue())
+
+    def initialState(self):
+        return "hover"
+
+
+class ShooterIdle(State):
+    name = "idle"
+    detectRange = 150.0
+
+    def update(self, owner, world):
+        if owner.cooldown > 0:
+            owner.cooldown -= 1
+        if owner.playerDistance(world) < self.detectRange and owner.cooldown == 0:
+            owner.facePlayer(world)
+            return "aim"
+        return None
+
+
+class ShooterAim(State):
+    name = "aim"
+    windup = 18
+
+    def update(self, owner, world):
+        owner.facePlayer(world)
+        if self.timeGuard(owner):
+            return "fire"
+        return None
+
+    def timeGuard(self, owner):
+        return owner.machine.timeInState >= self.windup
+
+
+class ShooterFire(State):
+    name = "fire"
+
+    def onEnter(self, owner, world):
+        target = world.player
+        dx = target.centerX - owner.centerX
+        dy = target.centerY - owner.centerY
+        distance = math.hypot(dx, dy) or 1.0
+        speed = constants.projectileSpeed
+        projectile = Projectile(
+            owner.centerX - 3,
+            owner.centerY - 3,
+            (dx / distance) * speed,
+            (dy / distance) * speed,
+            owner="enemy",
+            damage=1,
+        )
+        world.spawnProjectile(projectile)
+        world.playSound("shoot", owner.centerX)
+        owner.cooldown = constants.shooterCooldown
+
+    def update(self, owner, world):
+        return "idle"
+
+
+class Shooter(Enemy):
+    kind = "shooter"
+    hasGravity = True
+    stompable = True
+
+    def __init__(self, x, y):
+        super().__init__(x, y, 16, 16)
+        self.hp = 2
+        self.cooldown = 0
+        self.machine.addState(ShooterIdle()).addState(ShooterAim()).addState(ShooterFire())
+
+    def initialState(self):
+        return "idle"
+
+    def update(self, world):
+        if self.hasGravity:
+            self.vx = 0.0
+            self.vy += constants.gravity
+            if self.vy > constants.maxFallSpeed:
+                self.vy = constants.maxFallSpeed
+            physics.moveVertical(self, world.level, world.platforms)
+        super().update(world)
+
+
+enemyFactory = {
+    "goomba": Goomba,
+    "chaser": Chaser,
+    "flyer": Flyer,
+    "shooter": Shooter,
+}
+
+
+def spawnEnemy(spawn):
+    factory = enemyFactory.get(spawn.kind, Goomba)
+    return factory(spawn.x, spawn.y)