I have some criticism that you should really take into account.
1: The double jump is inconstant, sometimes you can't do it.
2: The revolver is better than every other weapon in damage and accuracy so here are my weapon fixes:
a: Make the revolver have perfect accuracy so it is best for ranged combat, but reduce its fire rate.
b: Reduce the damage and accuracy for the rifle, but give it better fire rate (If you want make it so it looses accuracy the longer you hold down the trigger)
c: Increase the damage and range of the shotgun, it is outclassed by every weapon even in close range
3: Add a low performance mode, the fps was very inconstant on my lower end computer and dipped constantly from 100 to 20 fps. My fix would be to add a frame rate cap of 60fps to avoid dips and make it more smooth.
4: Have an option to reduce camera and weapon bob. The game induced motion sickness after only a few minutes.
5: Add some weapon knockback to dead enemies. When you kill a walker its head sort of just pops off. Make it fly off in the direction you shot it. If you want, have the decapitated body stumble around a bit before dying.
This may seem harsh, but I really want to see your game do well. Hope you use at least a few of these to make your game even better!