Fallout Shelter
It's made by Bethesda and it has Fallout in it's name... but Fallout Shelter is far from the company's open-world action RPGs. Instead, it puts you in charge of an underground vault where people are protected from the post-apocalyptic wasteland outside. You have to expand and maintain the vault, protect the inhabitants while keeping them happy, send some out to explore the desolate landscape, and even try to get them to mate so as to keep the human race going. You know, just your typical TEOTWAWKI stuff.