This game was cute! At first I was like "how in the world will I ever be able to win" because my zombies were barely able to hurt anybody. But then after a few rounds my zombies were unstoppable! I like how the power up system was implemented.
I think one thing that would've been cool is if outside the fence also had terrain even if you couldn't interact with it. Like instead of having a solid color, having trees and lights and pathways to make it seem more like a world.
Thanks for sharing!