Very enjoyable, loved the artstyle and the little nods to House of The Dead and Resi, rest of this comment is going to be little things about the game I wish were different but I really want to emphasize that I enjoyed it a lot.
- The collision on steps is wrong, the camera bobs up and down while you're going up and down them.
The easiest way to fix this would be to make the collision for the entire flight of stairs a ramp instead of conforming to the geometry of the steps.
- No ambient noise / music
This is ok, making music is really hard and no music is definitely better than bad music. It's very easy to make some simple pink / white noise ambience in Audacity and it adds a lot to a game, (video below covers this well) try it out and see how much better it makes your games feel.
- No reason to play the game the "fun" way
You have a really cool dismemberment system for the zombies but no incentive to utilize it. It would be cool if the zombies did a lot more damage and you could gib zombies legs with one pistol shot so that it was more efficient to shoot them and leave them alive than it is to kill them outright
Good work though, looking forward to anything from you in the future