If you want to just goof around, use any chess program (such as OSX's built-in Chess.app) set at the hardest difficulty, and play the opposite color from your r

If you want to just goof around, use any chess program (such as OSX's built-in Chess.app) set at the hardest difficulty, and play the opposite color from your real game. Then copy your opponent's moves to Chess.app, and make the computer's moves in the real game.