It really was tough to choose a winner. All the games were fairly polished and fun. They all had the same weakness: repetitive gameplay. It was ridiculously close.
The winner, due to being a tiny bit more polished and fun was:
Take That, Zombies! by Zack
This game had fun gameplay, decent graphics, and good overall polish. Being able to change the colors and an online scoreboard helped round out the game. I probably played this game the most while trying to pick a winner, it's simple but mildly addicting.
That isn't to say that this game is perfect. Powerups would have been a nice addition and there are glitches when zombies are directly above or below you. The player animation could have used work, it looks a bit odd. The game felt rather pointless after a while.
I'm not saying that Take That, Zombies is a bad game, it just doesn't feel like it's quite finished. I would be quite happy to see the creator expand on this fun little game.
Congratulations Zack, and thanks to all who entered. There wasn't a single entry I didn't enjoy playing.
Other entries (in order of entry):
Psychodelic Zombie Assault - A fun little top down game that only occasionally gives people seizures, made by yours truly.
Quogog - Small, fun arcade game that doesn't really have much to do with the theme as far as I can tell.
Irving the Serial Killer - A scrolling platform game with great graphics and very odd gameplay.
Circum Skull - A fairly well polished but rather repetitive little arcade game with online hi scores.