Fox's democracy co-GM idea is a great one. As is the reboot. We could begin as the characters who already know each other have (somewhat reluctantly/are forced to) leave the countryside for whatever reason (perhaps the fight in town attracted too many zombies, or someone got infected and they had to get out fast). 

They've lost some friends and the mall is their best bet for supplies.

[b]EDIT:[/b] It might be an idea to come up with something else that sets this zombie apocalypse apart from the rest if we're going to recruit people.