Nice little game. I liked how it was focussed around pushing the zombies away from you. You sorta had to manage both sides of the level by ensuring that you have space so to speak. The feeling of punching the zombies was also pretty cool.
That said I do have some criticisms. I think the player could've used more feedback when it came to getting damaged. I wasn't sure when or how I was getting damaged. Along with that, I think the hitbox of the zombies wasn't really as clear as it really should have been.
I also think some sort of UI indicator or something for the super punch would've helped me to prime myself to be more strategic with it.
All that said though, I think the art is really good. It's grungey in a newgrounds way that definitely fits the tone that you were going for with this game. All in all, I'd say this was a cool little entry