Excellent work.
This was a great game, not to mention one of the few zombie themed games I enjoyed playing more than just once. If you plan on making a sequel I have a few suggestions. It would be nice if there was difficulty settings to make replaying the game even more challenging. Also it would be nice if there was some kind of bosses or unique zombies that were especially hard to kill and especially quick at destroying your barracade. Finally, like many players have suggested, it would be nice if there were explosive weapons, at least a limited number for crowd control.