move source files to separate folders

source/game/Simulation.gd

@@ -0,0 +1,12 @@
+class_name Simulation
+extends Node
+
+
+# Called when the node enters the scene tree for the first time.
+func _ready():
+	pass # Replace with function body.
+
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(_delta):
+	pass