Sun died,Neo-Thermal Generators used to counteract the cold, but they were inefficient,causing the planet to fall into a eternal winter storm in an event called "The Collapse" Attempts were made to evacuate the people, however many were left on their own,called "Scavs" which mostly consist of criminals. A contagious "systemic infection" floods the air and infects anyone, with many habitants being immune. It is way more deadly in the storm.