In the 27th century of the Earth's calendar, a cataclysmic cosmic event known as Metacron occurred, dividing the cosmos into five main realities. After the separation process, the energy balance is lost, rendering these dimensions incapable of sustained existence. As these dimensions gradually collapse, life throughout the cosmos is driven to the verge of extinction.
Area 53 - the last point on Earth where energy balance exists and where the five dimensions converge - becomes the last area capable of supporting life. Thus, empires from all dimensions flock to this location, fighting for their last shot at survival.