< Day Day Up >

---

Chapter 11: Defining Rules

Overview

The rules of chess, of course, state how the pieces may be moved; they distinguish between legal and illegal moves. Since the knight, for example, is permitted to move only in a highly restricted manner, it is clear the permitted means for moving the knight are of less scope than the possible means for moving him.—Bernard Suits, Grasshopper: Games, Life, and Utopia

What are game rules? Let's begin with a simple example, one of the most minimal games we can find: Tic-Tac-Toe. The game of Tic-Tac-Toe is defined by the following set of rules:

1. 
   

   Play occurs on a 3 by 3 grid of 9 empty squares.

   
   


2. 
   

   Two players take turns marking empty squares, the first player marking Xs and the second player marking Os.

   
   


3. 
   

   If one player places three of the same marks in a row, that player wins.

   
   


4. 
   

   If the spaces are all filled and there is no winner, the game ends in a draw.

   
   

These four rules completely describe the formal system of Tic-Tac-Toe. They don't describe the experience of playing the game, they don't describe the history and culture of the game, but they do constitute the rules of the game. These four rules are all you need to begin playing a game of Tic-Tac-Toe.

Astonishingly enough, these simple rules have generated millions and millions of hours of game play. Armed with these rules, any two Tic-Tac-Toe players can be assured that when they begin play, they will both be playing the exact same game. Whether played in front of a computer terminal or scratched in the sand of a beach, every game of Tic-Tac-Toe shares the same basic formal identity. In this sense, rules are the deep structure of a game from which all real-world instances of the game's play are derived.