"At the Game Developers Conference this week in San Jose, two roundtable discussions will be dedicated to the topic of "game design methods" -- that is, methods for planning and defining gameplay. To set the stage, this article presents a cursory overview of past and present efforts to define structured, formal game design methods. Compared with the vast body of operational knowledge found in the world of filmmaking, the game design community is just beginning to articulate the concepts and techniques specific to our medium in order to establish methods of game design. What should we expect of a game design method?"
Gamasutra (requires registration): Game Design Methods: A 2003 Survey
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