A game that is similarly free-form, albeit less chaotic, is Eleusis. It is played with cards, and each round one person chooses a secret pattern, and the other players play cards, which are identified as correct or incorrect, and they try to figure out the pattern. So there are meta-rules about how the game is played, but the rules for "correct" cards change every game. It seems like a game many HNers would enjoy.

[1] http://en.wikipedia.org/wiki/Eleusis_%28card_game%29