Impressive work!
I really liked the overlay of the map. The zombie AI was neat, maybe with an update you can improve some details. The shooting was a bit odd, because I had to press RMB, instead of LMB to do that, but again, with a project like this, you have a potential. I would suggest changing the default assets and have a different look, you know, add a different terrain or a house.
Best of luck with the future installment!