Soren Johnson gave a similar talk on AI Playing to Lose: AI and "Civilization"[0]. Here he split AI into two groups, Good AI(Chess) and Fun AI(Tower Defense), While the good AI plays the same game as you with the same rules and tries to beat you,Fun AI is asymmetrical, playing a different game whose objective is not to beat you, but you might still be defeated.
[0]http://www.youtube.com/watch?v=IJcuQQ1eWWI