I've made several different zombie modes. Zombie/infection are my favorite, right after grenades only.
Anyway, I have one similar to "FAT KID"... >_> But it's not...
Anyway, it is a slow zombie with a hammer and laser, regular infected with fast speed. Played on Jankytown. Why Jankytown? It's maze ish, but it was a Bungie made varient (Yeah, Bungie), and there are three levels to it. Alpha Zombie, or as I called him, the Nemisis (RE for the lol) has insta kill. I've made alterations to his health, and probably still will. I want him to be slow, not die easily (nothing you can do about assassinations), but not impossible.
I have others, including one made for Sandtrap, called WW:Z. FAST zombies with hammer and sword, and humans with BR and vehicles.
Others too.