You, uh, you do know that the "Under" part of UnderRail refers to the underground nature of the game world, yeah? Not a lot of day in a cave. And survival mechanics have been discussed before, but this isn't a survival game. That would be rather a lot of work to add an element that doesn't belong in the game.
Procedurally generated quests might be interesting. With the expansion, we see that there's a lot more to the game world than just the immediate map areas and North UnderRail. But where do they spawn, and when? Do they spawn in uncleared zones? If so, does the existing population kill them? Do they spawn only in cleared zones? UnderRail isn't designed to have a lot of backtracking - for the most part, you explore and area and then you're done with it. The existing random encounters seem like they're what you suggest, maybe you just want their spawn rate increased a bit?
