So I was messing around by scrounging door to door from town to town and I wound up having a pretty interesting time. I think a mission based in random towns would be an interesting idea. It was a lot more interesting not knowing where AI might be coming from next and zombies become a much more interesting aspect when you're taking cover and can't move and start to swarm on you 10 at a time.
A couple details, a loot box could spawn randomly in a town, but I think it'd be better (though maybe impossible) if the loot for a general location could be changed during the mission. Maybe the city is a new base of operations for bandits and it spawns more rare and more guns or starts to spawn gold or sparsely gems. If it were possible to make ai spawn a little more frequently for the location or UAZs that'd be pretty interesting too. It would be pretty similar to kill city, but hopefully not 'quite' as difficult. And if the loot spawned in various locations it'd be a little more interactive in searching and no one could just remember one location or get lucky early on because they'd need to keep looking for more. I certainly think we could use a few missions that require a little less sniping or at least isn't the only option most of the time.
Also, it could either appear as a mission or like the patrols that spawn and wander the maps. (I still haven't managed to run into those. Are they just hazardous or is it rewarding at all killing them?) Or it could be for 30 minutes a town spawns better loot and more ai or etc. And of course it could be cities or towns or whatever seemed to work best.