Nomic is a game invented in 1982 by Peter Suber, as an appendix to his PhD thesis The Paradox of Self-Amendment. In Nomic, the primary move available to the players is to change the rules of the game in a structured way. Nomic itself was intended as a minimalist study of procedural law, but it has been played very successfully by many groups over the years.
I first played Nomic through Agora, a long-running Nomic of a heavily procedural bent (as opposed to variants like BlogNomic, that have developed in much more whimsical directions). I've found the game, and the communities that have sprung up around the game, deeply fascinating as a way to examine how groups reach consensus and exercise decisions.
I briefly experimented with the notion of running a procedural Nomic - a mini-Agora - via Github, and produced two documents: