Nomic

In the words of Nomic's author, Peter Suber:

    "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."

Players start off following some "initial rule set", and gameplay occurs in clockwise order, with each player taking a turn. In that turn, they propose a change in rules that all the other players vote on, and then roll a die to determine the number of points they add to their score. If this rule change is passed, it comes into effect at the end of their round. Any rule can be changed with varying degrees of difficulty, including the core rules of the game itself. As such, the gameplay may quickly change.

Rules are divided up into two types: mutable and immutable. The main difference between these is that immutable rules must be changed into mutable rules (called transmuting) before they can be modified or removed. Immutable rules also take precedence over mutable ones. A rule change may be:

 the addition of a new mutable rule
 an amendment to a mutable rule
 the repeal of a mutable rule
 the transmutation of a rule from mutable to immutable
 or the transmutation of a rule from immutable to mutable

The game can be played around a table with written notes, or online through mailing lists or forums. Alternative starting rulesets exist, particularly for online and postal games which don't suit the usual clockwise turn order. Several games have been running online for over a decade.