feat: Implement core game mechanics including player, enemies, bullets, HUD, and level setup.

scripts/enemy.gd

@@ -0,0 +1,65 @@
+extends CharacterBody2D
+
+@export var speed: float = 100.0
+@export var max_health: float = 100.0
+var current_health: float
+
+var player: Node2D
+@onready var health_bar = $HealthBar
+@onready var turret = $Turret
+
+@export var bullet_scene: PackedScene = preload("res://scenes/bullet.tscn")
+@export var fire_rate: float = 2.0
+var can_shoot: bool = true
+
+func _ready():
+	add_to_group("enemy")
+	current_health = max_health
+	if health_bar:
+		health_bar.max_value = max_health
+		health_bar.value = current_health
+		health_bar.hide() # Hide initially, show on damage
+
+	# Find the player in the scene tree
+	player = get_tree().get_first_node_in_group("player")
+	if not player:
+		# Fallback: try to find by name if group not set
+		player = get_parent().get_node_or_null("player")
+
+func _physics_process(_delta):
+	if player:
+		var direction = (player.global_position - global_position).normalized()
+		velocity = direction * speed
+		rotation = direction.angle()
+		move_and_slide()
+		
+		# Aim turret at player
+		if turret:
+			turret.look_at(player.global_position)
+			
+		# Shoot if close enough
+		if global_position.distance_to(player.global_position) < 400.0 and can_shoot:
+			shoot()
+
+func shoot():
+	var bullet = bullet_scene.instantiate()
+	bullet.shooter_group = "enemy"
+	get_tree().root.add_child(bullet)
+	bullet.global_position = turret.global_position
+	bullet.global_rotation = turret.global_rotation
+	
+	can_shoot = false
+	await get_tree().create_timer(fire_rate).timeout
+	can_shoot = true
+
+func take_damage(amount: float):
+	current_health -= amount
+	if health_bar:
+		health_bar.show()
+		health_bar.value = current_health
+	
+	if current_health <= 0:
+		die()
+
+func die():
+	queue_free()