This was a really simple fps zombie shooter. It would be much better if more things can be done in the game like reloading guns, changing guns, larger maps, using grenades, melee weapons etc. You can reference games like Back 4 Blood, Call of Duty: Zombies, Left 4 Dead, Zumbi Blocks etc. for more inspiration on what to add into a zombie shooter game.
Thank you for reading my comment and I wish you good luck in your future endeavours.