Shut away beneath the desert of what may not have been a desert before, a family clings to the remaining vestiges of their old life as best they can. There are few left. Mother's cooking has given way to regimented rationing. Father's work now revolves around the maintenance of life support machinery, a task for which for his suit and tie is ill-fit. The kids have no friends; those remaining outside the fallout shelter are less than amiable. Now, a choice needs to be made: will one or both of the parents venture to the surface, risking the possibility of their family persisting without them, in search of supplies? Or do they wait? Conditions might improve. Or the family could simply be fruitlessly burning the candle.
I don't know if Sheltered is going to play like this. I hope it will – it certainly represents an immense potential for pathos, for racking you with guilt when your actions bring misfortune or washing relief over you when somebody comes back alive.
The developers have suggested outside survivors like stray mother-child pairs or ex military hunting parties attempting to gain entry and random encounter generation. The phrase "as an ant farm" has been stated with respect to the play style. Features and mechanics are definitely in the air, but we'll probably learn more details their planned Kickstarter campaign tees off.
Until then, I'll be keeping an eye on Sheltered.