[shaggyfrog]

Won those games against whom? Other copies of itself? The weakest built-in AI? The strongest built-in AI? A pseudo-random number generator?

[wlievens]

Built-in AI. They didn't specify the difficulty level, but knowing Civ games (can't speak for FreeCiv though), difficulty levels only tweak handicaps and not the AI algorithms, so the correct choice would be the difficulty level that has no handicap or bonus for the AI.