Everything changed with the arrival of the Traveler. It sparked a Golden Age when our civilization spanned our solar system, but it didn't last. Something hit us, knocked us down.
The survivors built a city beneath the Traveler, and have begun to explore our old worlds, only to find them filled with deadly foes.
You are a Guardian of the last safe city on Earth, able to wield incredible power. Defend the City. Defeat our enemies. Reclaim all that we have lost. Fail and the last light of civilization will go out.