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. Be brave.