

Project Zomboid. There is a whole city for players to mess around in. You can just host a server and let it run, friends can join any time. The current version doesn’t support multiplayer for now, but the one before that does.
I would suggest separate bases for every player, if you don’t want Jerry to let a ton of zombies into the communal base, because he played without the others around to tell him to close the god damn door behind him for the hundreth time!
Depends on where they spawn, the map is very large. But yea, friends joining the group late wouldn’t have much to do.