They say there were once billions of people who lived on this earth before the Great Rain. The murderous, toxic rain. But our ancestors saw it coming, and before the rain came, they built a sphere of life, where it's safe to breathe the air, and it's safe to drink the water. They called it: Eden. But Eden was not big enough for everyone; refugees came, by the millions, but our ancestors turned them down; left them to die in the waste land. And the few hundred that survived were forced to work for Eden, to maintain it from the outside, where few of us dared to go. We called them the Keepers. We need them, and they need us, everyone wins. But some win more than others.
Everything started in 2036. The pollution was so bad that the end of the world was predicted to be right around the corner. As complete panic set in around the world, the rich and important people were all gathered and placed on giant spaceships with enough resources and room to house generations of human beings. Before they left though, the government leaders fired As a result, most of the human population died off and earth was a complete wasteland. The little that survived started building local communities and trying to survive in the destroyed excuse of a planet.
On the disaster of a planet, creatures mutated and were born out of the nuclear chemicals; creating new species and monsters that hunted humans. While hundreds and hundreds of years passed, the monsters kept evolving and the people kept adapting while still trying to keep a sort of community. They didn't want to lose all of their humanity and become nothing more than animals that hunted the monsters: then they would truly be no better than the monsters themselves. So they stayed civil while still doing what it took to survive.