Switch to KinematicBody2D so we can think of walls etc

characters/player/Player.gd

@@ -1,4 +1,4 @@
-extends Area2D
+extends KinematicBody2D
 
 
 export var speed = 200 # How fast the player will move (pixels/sec).
@@ -8,8 +8,7 @@ var screen_size # Size of the game window.
 func _ready():
 	screen_size = get_viewport_rect().size
 
-# Called every frame. 'delta' is the elapsed time since the previous frame.
-func _process(delta):
+func _physics_process(delta):
 	var velocity = Vector2.ZERO # The player's movement vector.
 	velocity.x += Input.get_action_strength("move_right") - Input.get_action_strength("move_left")
 	velocity.y += Input.get_action_strength("move_down") - Input.get_action_strength("move_up")
@@ -20,6 +19,4 @@ func _process(delta):
 	else:
 		$AnimatedSprite.stop()
 	
-	position += velocity * delta
-	position.x = clamp(position.x, 0, screen_size.x)
-	position.y = clamp(position.y, 0, screen_size.y)
+	self.move_and_slide(velocity)

characters/player/Player.tscn

@@ -14,7 +14,7 @@ animations = [ {
 [sub_resource type="CircleShape2D" id=2]
 radius = 23.0217
 
-[node name="Player" type="Area2D"]
+[node name="Player" type="KinematicBody2D"]
 script = ExtResource( 2 )
 
 [node name="AnimatedSprite" type="AnimatedSprite" parent="."]