Legend tells of a cave so big that the roof cannot be found, so wide that there are no walls. Once, the stories say, we lived there, and a ball of lava rolled across the roof of the cave and filled everything with warmth and light. When the ball of lava hardened, the cave grew dark and cold. So cold that the people went down into the smaller caves, where the fire below gave warmth and light.
Thousands of years ago, the planet Subterra was flung out of its orbit, and spun away into the vast empty reaches of space. Though the surface is now a desolate wasteland of ice and barren stone, life continues underground. In the caverns and tunnels beneath the surface, desperation has turned to adaptation, and what were once fearful bands of refugees struggling to survive have made a new place for themselves.