Grey screen in BlenderGame

Dear Comunity,

i made a clone of asteroids in blender and shortly before i finished it, Blender shows a grey screen. When i start Gameengine its grey, and when i render its Blue. I don´t know what has happened. I tried to restart Blender, but it doesn´t work. Other files worked correctly. Its not the camera, i tried to check the blender game outside of it.
Please help me, i don´t want to waste the game because of a false setting.

Codedoc

Screenshot:


.blend-File:
asteroids.blend (812 KB)

i could be wrong, but it just looks like you set everything to invisible in the physics tab

can be:
-The normals of the plane
-Invisible physic activate.
-Invisible material option activate.

I thinks are the normals.

You just disabled render in the outliner (left upper corner the camerabuttons).
If you enable them you can play the game, and the render works too.
(I hope i got your problem right or did you want to change the backround and disabled the objects render?)

Thanks for the quick help. Now i can see all Objects again. For me its verry hard to find mistakes, because im nearly beginner in Blender.