Added shield and score UI; player collision signal connected to enemy

scenes/EnemyBullet.gd

@@ -0,0 +1,17 @@
+extends Area2D
+
+@export var speed = 150
+
+func start(pos):
+    position = pos
+
+func _process(delta):
+    position.y += speed * delta
+
+func _on_visible_on_screen_notifier_2d_screen_exited():
+    queue_free()
+
+func _on_area_entered(area):
+    if area.name == "Player":
+        queue_free()
+        area.shield -= 1