I'm embarrassed to admit the game was mostly content complete by the original deadline - I'd made the final level and endings, I just hadn't completed (or begun work on) the fourth level. Still, once I got over my procrastination, I got to add sound and other polish to the rest of the game (the bit with the room full of zombies in level 3 was always there; the bit where a pair of them were literally trying to tear down the door was not XD)