I am not really sure to get why the title screen is an anime girl and what's up with the girl sounds so I will just ignore them.
My heart almost stopped the first time the gun sound is played on the title screen, it's too loud ^^
There is something weird with the reload, I think that after I do it once I briefly see it start over. It would be nice to have more feedbacks: when you hit something, the damage you did, the health remaining on the zombies and the purpose of the style.
Congrats on making an FPS.