I think body carrying is a big one, to make sure you stay undetected.
The biggest thing I would actually like to see, I think, would be like a hub world? Immersive sims are usually pretty level based so something like a Fallout 1&2 map with some being more dungeon focused and some just being towns with normal quests, would be ace.
But generally, I just want a fun experience with cool level design. I think that is the biggest thing.
