Try to keep it realistic, in the margin of a zombie survival action-rpg hybrid game, and clean.
I wanna add more parts dealing with survival, having been watching "The Colony" it kind of motivated me to add more of that aspect into the game.
The suggestions can range from types of zombies, buildings, weapons, etc. Just follow the guidelines above.
-Can't be killed.
-You lose as soon as he appears on the screen.
-Mind-rapes the player because Chuck Norris can't die.
-He has a beard.