The rules of any game exist on three related levels: constituative rules, operational rules, and implicit rules.
Constituative rules are the abstract, core mathematical rules of a game. Although they contain the essential game logic, they do not explicitly indicate how players should enact these rules.
Operational rules are the "rules of play" that players follow when they are playing a game. Operational rules direct the players' behavior and are usually the kinds of rules printed out in instructions and rulebooks for games.
Implicit rules are the "unwritten rules" of etiquette and behavior that usually go unstated when a game is played. Similar implicit rules apply to many different games.
The operational rules for any particular game build directly on that game's constituative rules. However, any given set of constituative rules can be expressed in many different operational forms.
There is a fuzzy boundary between operational and implicit rules. For example, sometimes a game designer may make certain implicit rules explicit by including them in the printed rules of a game.
The formal identity of a game allows us to distinguish a game as formally unique and distinct from other games. This identity emerges from the relationship between the game's constituative rules and operational rules.
Key in establishing the formal identity of a game is the specificity of the rules. The exact and unambiguous nature of the constituative and operational rules allow a game to be this game and not that game.
There is a translation that occurs among the constituative, operational, and implicit rules of a game. The magic circle is the context for this translation. The formal meaning of a game emerges through a process that bridges all three levels of rules in a game.
Elegant rules allow players to focus on the experience of play rather than on the logic of the rules. Designing meaningful play involves building discernable and integrated relationships between action and outcome into all levels of the rules of a game.