you're right loopix
but I had worries (thats why I asked ).
when I image a casual gamer I see a total newbie who doesn't know what to do with a PC. now, the game ask you for tje IP of the server... hmm not very casual
the problem isn't really to program the single player, I can just use the code from the multiplayer.
but I have to create more levels... well I will finish the multiplayer part today so I have some days to create the single player part.