Ultimate Gin

Quoted from one of the author at Accidental Software:

Ultimate Gin had an A.I. element to it. We actually didn't realize we were designing and programming A.I., as we just wanted the game to learn the player's strategies, but not cheat. After the release of the game, universities and researchers called us to see if I would tell them how we did it. They were more surprised when I told them, since most companies would have held onto it as a trade secret. We had our own server, but no longer.