Animations and audio where great. I enjoyed the sound the shovel made. I felt like I should be able to swing the shovel even when not near a zombie.
I feel like there should have been more of a difficulty scale as when the zombies really started coming, I just stood in the same path and kept smacking them. (still satisfying).
Maybe having more zombies spawning and another exit for them to escape. (Like mirror the grave yard with some zombies moving up and some moving down.
Great submission!