One of the cool ideas I want to play with in the zombie apocalypse game is the idea of a dungeon in reverse. What I mean is using the dungeon not as the dangerous area where people explore to gain loot, but rather as a haven, where characters return to after forays into the outside world. I know this could be done with the "monsters as characters" trope, but I'd like to do it with a traditional adventuring party.
The way I envision it, the adventuring party is part of a group that has fled to a dungeon or nearby series of caves in order to shelter from an impending disaster. They've brought some supplies, willing to risk the uncertainty of the dangerous dungeon rather than whatever is happening in the outside world. Eventually, they venture forth to see what awaits them, but the dungeon remains as a place where they return to take shelter. Of course, areas of the caves are unexplored and dangerous, spawning monsters to menace the party upon occasion.
I just think it would be cool to reverse the gaming standards of "safe zone" and "dangerous dungeon."