You put a lot of work and thought into this game. You're giving potential players a way to look at zombies from several different angles. I know it's supposed to be kind of silly too but there's also a way in which the game can be approached as tragic or melancholy/brutal as well. In fact, with the survivors there's really an element of bloodthirstiness baked in (and I don't mean the zombies feasting, lol). The document is well designed and easily readable. The green is just the right color to keep things legible and comfortable for the eye. Your use of the storefront page is smart and tells potential players EXACTLY what they're getting into, which is very important.
The mechanics of losing body parts and augmentation is a good one and allows for some agency during session. I'm not sure the GM portion is necessarily needed since it doesn't have much elaboration. By that I mean there's no section really focused on them, their role, and how they can really help the game. However that's just a small critique because I think the group taking turns deciding things works better with your system - but I also see if from the perspective of...an experienced GM/DM will take this concept and really throw a group for a loop so...why not?
Good work overall!