Go, a.k.a. Badu (South Korea) and Wei-chi (China), is considered
to be the ultimate thinking game. Its simple rules hide a game
of enormous depth. In consequence computers, who have mastered
Chess, have only reached low amateur status in Go.
Go++ was written by Mick Reiss, who has worked on it for 25 years. This game engine is stronger (and larger) than Aya, has won many competitions and was invariably ranked with the top 2 programs. It is available under a number of products in Japan and the West.