Overall, I really liked the game. I like how it feels when shooting, and the three different weapons are satisfying.
At times, I felt stuck because of the hitbox of some elements that I think are too big. It's a little hard for me to tell which elements can be traversed on the terrain and which cannot.
It lacks a bit of a sense of progression, maybe a final boss or something every so often, or bigger zombies.
I tried to heal myself by killing chickens with the chicken, but it wasn't clear to me whether I could heal myself or not. I would add elements such as first aid kits or other power-ups. It might also be fun if some zombies dropped loot.
Overall, it's a good game with potential.