Thanks for nice comments. I will implement the other objects, which exist already, like flamethrower, in the next levels. @ Game/maniac : I can send you a jar file if you want to try.

I thinks, that isn't possible because the whole scenario stops. But maye you could implement a boolean variable called break. If the player loses it would be true. And all act-methods of all classes, EXCEPT the time-counter will only work if break==false. So if it is true nothing will happen. I made it this way in my game.