20 days of Zombie hordes
I really enjoyed this game. Wave upon wave of zombies marching on my little makeshift wall, armed only with what weapons I could scrounge and the help of poorly armed random survivors.
I did have some slowdown issues in the later levels as the piles of zombie bodies started getting larger, but other than that, pretty solid.
I think the highlight was around night 15 when out of nowhere a clown zombie bolts across the screen. I laughed... then I shot the freaky clown-zombie.