I wish there was a "realistic" modern post apocalyptic RPG where you can interact with just about everything in game and do whatever you want. The health system should be extremely realistic with the ability to lose limbs/appendages, have side effects from using medicines, side effects from things like blood loss, and perma death where you start over as a new person when you die.
You would spawn in a room in a relatively safe part of a town but with few supplies and only a bag with basic necessities (water filtering kit, knife or blade of some sort, bed roll/sleeping bag, some food, etc) with the starting supplies being of random different qualities so each time you spawn you could get really good equipment, really bad equipment, or a bit of both. Everything you interact with wolf affect future game play.
Ex: if you loot the starting "safe" area on your first run through then die, the next character will spawn in the safe area but all the loot (discluding starting equipment) would be with your now dead character or where you left it.
The maps should be procedurally generated with no specific missions just surging and maybe helping others out or trying to kill of raiders or become a raider and such. Maybe even have randomly generated factions.
You should be able to interact with other survivors and maybe even start your own faction.
Areas would have verrying levels of difficulty. From places like the spawn area where there are no threats to you but little to no loot. To relatively dangerous places with raiders or slavers roaming about but plenty of loot. All the way up to Chernobyl like areas where something like radiation or biological hazards are everywhere and one wrong step could kill you.
I think the apocalypse setting should be relatively realistic or maybe even randomized.
So if you get tired of playing in one world you could permanently reset it (or save it) and start a new one to play in.
Going along with the previous statement, new worlds/maps would have a chance at being made by different apocalypses that caused different things to happen. Maybe one was from a world war so all the buildings are destroyed and there are heavily irradiated areas from nuclear bombings or bio hazard areas from old attacks. Or maybe the world was ended by a plague where there are few survivors and the streets are littered with the dead, so you would have to avoid getting sick, but the infrastructure would be relatively intact as nothing had really been there to destroy it.
I think this would be a pretty amazing game if it existed and I would most definitely buy it if it existed.
(Side note- modern apocalypse= guns and a realistic variety at that (as well as realistic ammo scarcity))