hmmm what if the game had a major virus and the way to travel between areas was the apartments
just putting it out there as you could reasonable say there was nonething in the open expance besides zombies could also make for some interesting encounters
tho my thought is your making a more normal life sim over dead world style
it could be cool to have one but its a decent under taking so id suggest maybe limiting yourself to a small city with key locations and well you could make none explorable stuff just boxes no need to detail what you cant see after all