Very fun shooter. I tried to survive as long as I could and even did multiple retries. I sometimes got lucky with health and ammo drops but most times they were rare, I got swarmed before I could get any item drops. The game doesn't give you time to recover between waves of zombies, and the spawn rate is much much faster than the rate you get recovery items for health and ammo. Not to mention the zombies close the distance extremely quickly and there's no way to 'stagger' or stun them.
Still, I had a lot of fun. The gunplay feels very satisfying. And like others have pointed out, some doom-like soundtrack would go a long way of making this game feel more intense and exhilarating. Nice game overall. Congrats!