Rules

Rules may be defined as statements and directions that must be followed within a given game in order for it to be played correctly. They are often fixed as "rulesets," created by the game designer and agreed upon by the players. The interactions between rules create the formal system underlying any given game.

Jesper Juul and Rules
In Chapter 3 of his book Half Real: Video Games between Real Rules and Fictional Worlds, game studies theorist Jesper Juul writes that rules both limit actions players may take and set up potential actions that are meaningful in the game world (55-57). Rules create a "state machine" for player actions -- when one player inputs an action (say, moving a piece), if follows a specific series of transformations through interacting with the rules (i.e. receiving points).

Parlett's Rule Analysis
In Chapter 10 of The Art of Game Design: A Book of Lenses, game designer Jesse Schell discusses rules an important category of game mechanics. He draws heavily on game historian David Parlett's taxonomy of rules, and reproduces it in his own work (145-147). In addition, Schell considers goals to be rules (the most important type, in fact, 148). A good goal has three traits:
 * 1) Operational Rules -- simply "what the players do to play the game;" rules at their most basic level (i.e. rolling a die)
 * 2) Foundational Rules -- the mathematical representation of the more colloquial operational rules (i.e. obtaining a random number between one and six)
 * 3) Behavioral Rules -- implicit to gameplay; sportsmanship (i.e. not tickling another player during a game of chess)
 * 4) Written Rules -- the documented version of operational rules (the instruction manual)
 * 5) Laws -- rules formed when games are played in serious, competitive settings; "tournament rules" (banning certain characters in a fighting game tournament)
 * 6) Official Rules -- written rules that form when a community of players merges laws with operational rules (the rule of calling "check" was originally a community law)
 * 7) Advisory Rules -- tips to help people play better; strategies (playing the center in tic-tac-toe)
 * 8) House Rules -- rules created by players in response to a game's perceived deficiency (no tag-backs in a game of tag, for example)
 * 1) Concreteness (players understand it)
 * 2) Achievability   (players can attain it)
 * 3) Reward          (players want to attain it)