The Experimental Gameplay Project: create 50 to 100 games in 1 semester. New games every week.
The Rules:
each game must be made in less than 7 days
each game must be made by one person, including all art, sound, and programming
each game must be based around a certain "toy" ie. "gravity", "vegetation", "swarm behavior", etc.
The games aren't likely to keep you entertained for more than a few minutes each, but they are all fairly unique. I particularly like "Attack of the Killer Swarm."
"I have not actually recommended many games, and I'll go on the record here saying my track record is probably best in the industry." - schild