Gess

The computer version of a board game invented by the mathematical society of the University of Cambridge (also known as the Archimedeans). It is based upon chess but played on an 18x18 chequered board and all the pieces look alike (as in draughts). It is usually played on a Go board using the standard sets of stones. It's a two player game with rather complicated rules but is very well documented (in English!) and should be easy to pick up.