Nomic

I've been playing Nomic for nearly thirty years now, mostly Agora Nomic which is coming up on its 30th birthday in a couple weeks, making it the second-oldest active one that I know of. (Unless you accept the old joke about Canada being a nomic.)

Nomic was invented as a way to explore the Grandfather's Axe paradox as it applies to legal systems: if a legal system includes laws about how to amend the laws, and those laws are used, then is it the same system? What if every single law in the system has been changed at some point? (Agora has exactly one rule that has never been directly changed, though there are some attributes possessed by all rules that have been changed over time.)

Nomic typically starts with a set of rules that are mostly stripped down to just that "how to amend the rules" core, with the "other stuff governed by the rules" stripped down to something intentionally boring ("roll a die, gain that many points, first one to 100 wins") that the players will probably replace. Replace with what? That depends entirely on the whim of the players. Long-running nomics tend to establish cycles (come up with an idea, play with it for a few cycles of "Bob won that round", then ditch it when enough players get bored with it; sometimes there are multiple sub-games that can interact with each other). There can also be paradoxes when the rules trip over their own shoelaces, or scams when the letter of the rules turns out to not quite match up with the spirit.