myself, i would like to make a sandbox zombie experience. it would start as the outbreak begins. you could go multiple routes. go it alone or make a team. find shelter ranging from hotels, to abandoned homes, to (thats right) prisons. find makeshift weapons. use stealth against the undead, or go on a full assault to wipe out a general area. think fallout3 meets the zombie survival guide meets command and conquer. i'd prefer 3rd person, but 1st person would make for an unusual experience. the area would have to be huge and diverse. at least the size of san andreas. Lol as for other ideas, not everything needs to super logical. like a rough cut of some cool features you'd like to see