dunezone's Journal: Most Impressive Eluding Game AI

A recent question appeared on the front page that asked for the "Most Impressive Game AI", the question should have been "Most Impressive Cheating Game AI".

Artificial Intelligence is designed to defeat a human player, but in the end its not that the AI is defeating us fairly, its more then likely defeating us unfairly. We should be discussing games that have AI that best eluded us from figuring out they were cheating. So what have you encountered that situation that you thought was great AI but later down the road you found out it was cheating you into believing it was great AI?