New features and plenty of code still in testing. This includes a level select, basic inventory, and a basic HUD.

Player/Player.gd

@@ -0,0 +1,59 @@
+extends KinematicBody2D
+
+const ACCELERATION: int = 1000
+const MAX_SPEED: int = 120
+const FRICTION: int = 1000
+const HEALTH_SLICES: Array = [0, 20, 35, 50, 65, 80, 100]
+
+var health_index: int = 6
+var hud: CanvasLayer = null
+var velocity: Vector2 = Vector2.ZERO
+
+
+func _physics_process(delta) -> void:
+    var input_vector: Vector2 = Vector2.ZERO
+
+    input_vector.x = Input.get_action_strength('player_right') \
+        - Input.get_action_strength('player_left')
+    input_vector.y = Input.get_action_strength('player_down') \
+        - Input.get_action_strength('player_up')
+    input_vector = input_vector.normalized()
+
+    if input_vector != Vector2.ZERO:
+        $AnimationTree.set('parameters/Idle/blend_position', input_vector)
+        velocity = velocity.move_toward(input_vector * MAX_SPEED, ACCELERATION * delta)
+    else:
+        velocity = velocity.move_toward(Vector2.ZERO, FRICTION * delta)
+
+    velocity = move_and_slide(velocity)
+    return
+
+
+func load_hud(node: CanvasLayer) -> void:
+    hud = node
+    if hud.connect('add_currency', self, 'add_currency') != OK:
+        print('ERROR: HUD "add_currency" signal already connected.')
+
+    hud.update_health(HEALTH_SLICES[health_index])
+    hud.update_currency($Inventory.get_currency())
+    return
+
+
+func add_currency(amount: int) -> void:
+    $Inventory.add_currency(amount)
+    return
+
+
+func _on_Inventory_update_currency(amount: int) -> void:
+    hud.update_currency(amount)
+    return
+
+
+func _on_Hitbox_body_entered(body: Node) -> void:
+    if not 'enemies' in body.get_groups():
+        return
+
+    if health_index != 0:
+        health_index -= 1
+        hud.update_health(HEALTH_SLICES[health_index])
+    return