They game is fine, but it's Wayyyyy! to diffucylt, the main reason is that it's almost impossible to get the bullet once it has been shoot, beacuse the zombies will swarm it, a dash could help with this problem
also for some weird reason, i start with -1 points, the score text is also a sligthly bad color, since the dark baground makes it really hard to see.
sorry if I sound harsh I just wanted to point out somethings that could feel bad.
hope you can use the feedback :)