'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.'
After the arrival of the Traveler, humanity saw incredible advancements. Technology thrived and human lives were longer. But, after the Darkness arrived after hunting the Traveler, humanity was weakened down to a single city on planet Earth.
You play as a defender of that city - someone who can use the power of the Traveler - and must defend the sieged city from its deadly alien foes and the Darkness itself.