Nomic is a game in which changing the rules is a move. In that respect it differs from almost every other game. The primary activity of Nomic is proposing changes in the rules, debating the wisdom of changing them in that way, voting on the changes, deciding what can and cannot be done afterwards, and doing it. Even this core of the game, of course, can be changed.
Ok, it's not mafia (though it could BECOME Mafia.) But it involves the democratic process, and it could be a lot of fun!
The 'core' of Nomic is, as the above quote states, that the game is based around changing the rules of itself. The game begins with a round-robin format, where each player gets a turn he uses to propose some change to the rules, after which all the other players vote on whether they want to push it through or not. There is a point-allocation system whereby you get some amount of points each turn, and also more every time you vote against a rule that is actually pushed through. The initial victory conditions are either achieving some set number of points, or being the first player unable to take a turn.
But, of course, the rules for what constitutes victory can change. And that is, as they say, the game.
There's some information
here, and an example list of rules
here. I will probably modify them a little to accomodate forum-based play. I've tried to set this kinda thing up in the past, it's never really taken, but it's worth another shot! For people tired of Mafia but looking for some new social game that isn't quite so blatantly cutthroat, it could make an interesting change.