The idea of this one is that you're in the centre of a bitchin' automated bunker. Then, the zombie apocalyse happens, and there are a bunch of civilians that want into your bunker.

So, it's a puzzle game that involves getting the civilians in without letting the zombies in. The inside of the bunker will be like a maze of doors, but certain doors are all on the same circuit, so you can only open all of them or none of them. So, you have to work them through the system while keeping the zombies from getting too far.

Then, there are also defense systems, like rooms that fill with fire, incinerating everything within, or other such things. So, the idea is you can sometimes let the zombies in there without screwing the civilians over, and burn the zombies, allowing the people through.

Another potential puzzle element would be that perhaps there's a room where people can put on, like, fire-retardent suits, or something, so they can walk through the fire, but the zombies can't, once they've visited there.

Or, given hooks, they can cling to something, while the zombies are flushed.