Write an RPG in 24 hours, during November, in the Pocketmod format, without any numbers. Hard enough for you? Run as part of NaGaDeMon http://nagademon.com
larp is great as a poketmod, for all the rules fit in your pocket and larp would be great as numerless for rolling dices is not the best way to solve conflicts in larp.
Few questions: Can we upload only 1 game for the contest per person, or can a person make more than 1 game on different dates? Can the game be a "fan-game"? What I mean, is can the game take place in a existing IP (like ghostbusters or bioshock for example) as long as I won't use any copyrighted art?
Like Onix says. Avoid IP that's copyrighted, because, well, it's copyrighted and you're not allowed to mess with it. And you're to make the whole thing in 24 hours, as per the standard 24 hours RPG rules.