Colossus Chess 4 is a computer chess game. The game is customizable and you can monitor all your previous moves. It is even possible to see the computer thinking ahead and predicting your moves. The computer is hard to beat, and would win matches against other computer chess programs of the day. It can achieve the king-bishop-knight mate, which is the most difficult checkmate manoeuvre possible in Chess. It was written by Martin Bryant who was also the author of the White Knight chess games.