Add a spawn method

And call it with the start timer.

Main.tscn

@@ -39,4 +39,5 @@ rotation = -6.07153e-08
 position = Vector2( 245.983, 380.055 )
 [connection signal="timeout" from="MobTimer" to="." method="_on_MobTimer_timeout"]
 [connection signal="timeout" from="ScoreTimer" to="." method="_on_ScoreTimer_timeout"]
+[connection signal="timeout" from="StartTimer" to="Player" method="spawn"]
 [connection signal="timeout" from="StartTimer" to="." method="_on_StartTimer_timeout"]

Player.gd

@@ -1,10 +1,15 @@
 extends Area2D
 
 export var speed = 400 # pixel / sec
-var screen_size
+var screen
+
+func spawn():
+	show()
+	position = (screen.position + screen.end) / 2
 
 func _ready():
-	screen_size = get_viewport_rect().size
+	hide()
+	screen = get_viewport_rect()
 
 func _process(delta):
 	var velocity = Vector2()
@@ -25,8 +30,8 @@ func _process(delta):
 	
 	position += velocity * delta
 	
-	position.x = clamp(position.x, 0, screen_size.x)
-	position.y = clamp(position.y, 0, screen_size.y)
+	position.x = clamp(position.x, 0, screen.size.x)
+	position.y = clamp(position.y, 0, screen.size.y)
 	
 	if velocity.x != 0:
 		$AnimatedSprite.animation = "right"