End of the world is already very close, and you in no matter what was necessary to survive. You can dig underground. When you reach there, before you open a wide variety of rooms. Your goal - to go as deep as possible into the ground! In the meantime, you can settle on floors of all those wishing to escape, force them to work. In general, to do something like a hostel.
Additional Information from Google Play:
: 2.3.3 +
: 1 000 000–5 000 000
: 3+ years