1. When playing chess against the computer, sometimes the computer would perform a move called "castling of the king". But why are you never allowed to perform this move against the computer?

2. In chromium BSD, sometimes there is this HUGE green enemy ship that keeps spraying strong green ammo at you. Even if you manage to shoot at it it would not be destroyed. To me it seems the only way out is to keep avoiding it. How can I destroy it?
Thanks.

You should be able to castle your king also. But you have to understand the rules for castling. There cannot be any pieces between your king and the rook that you want to castle with. AND you can NOT have moved that rook or your king previously.