Game Fu

Game fu is a game-design challenge which has been run periodically on the 'Table-top roleplaying open' forum of rpg.net.

Entrants are given about a week to design and write a role-playing game that uses ingredients from a set list. Some of the contestants then judge the entries.

GavKen also has a site about this.

My Game FU is stronger the yours (5 games created)

My Game Fu is still stronger than yours (2 games created)

My Game Fu grows stronger yet! (5 games created)

Your game-fu is Weak! And obsolete! (competition running now!)