I really like the Java 4K [Game] Programming Contest, and have entered seven games so far:
MEG4kMAN (2009), a Mega Man clone featuring very old school graphics.
Left 4k Dead (2009), a zombie shooter game inspired by Left 4 Dead.
t4kns (2008), a real time strategy game.
Miners4k (2006), a game kinda inspired by lemmings and diggers. It won the 2006 competition!
[MISSING] Hunters4k (2005), a first person shooter.
[MISSING] Dungeon4k (2005), a dungeon exploration game.
Sonic Racer 4k (2005), a racing game with stolen sprites. I lost the source code for this.
I also made a game called Dachon4k, a gravity based shooter, but I never entered it.
Oh, and I forgot about l4krits, a luxor clone, that I never entered either.
I sometimes enter the Ludum Dare competition:
Prelude of the Chambered, a first person dungeon crawler.
There’s Metagun, a platformer with some unique weapons.
I made Bunny Press, a somewhat violent puzzle game.
The first time I competed, I made a game called Breaking the Tower in 48 hours. It’s not a bad game! It finished third in the LD12 competiton.
There’s the Infinite Mario Bros game I wrote for some mario themed competition. The source code is public domain now!