This is maybe not something that is quite as good for games, but it's 24 hour comics day, where you draw a page every hour for 24 hours, and get a 24 page comic at the end. If anyone wants to make a comic, or a game with 24 screens, that would be sweet. I think i'll try making a game like this, it remains to be seen how well it will work. Comics, being always about stories, often do have a length metric, and a big volume feels better to hold and navigate through. The same can't always be said about games, as many big games feel tedious at times, but maybe that's not because of the medium, but how certain people and groups approach it. This was just an extended free ramble, but i'm not editing it. Make a 24-screen game and post it here, or a 24-page comic, or both if you're REALLY REALLY AWESOME.

Here are the original directions for the 24-hour comic challenge, make them analogous to making games in whatever way you see fit.

Games made for 24-Hour Comic (GAMES) day