Lore

Descent: Underground is a prequel to the Descent series, and is set in an unknown amount of time prior to Descent 1. Earth has been torn apart by war and disasters and is dying of thirst. Some people have gone looking for a new place for humans to live in deep space, but they haven't returned yet. In the meantime, its only hope for survival lies in the gathering resources from asteroids by corporations, who are represented by larger-than-life pilots who are portrayed as heroes to the people of Earth. The corporations have taken over from the governments. There is a "gold rush scenario" for these corporations to get out to the asteroid belt and start harvesting the resources available there, with lots of fighting and lost pilots. The corporations made an agreement to use unmanned drones instead of piloted ships to cut their losses, but not everyone agreed. Some piloted ships remained, and other corporations took to designing robots to do the mining for them. The drones fighting over these resources is being broadcast back to earth.

There were "nice" corporations at one time, but the ruthless corporations eventually took them over.

History of the lore
While the game was called Ships That Fight Underground, there were to be several phases of development where the player would be able to go to the moon and the other planets in the solar system, discover aliens in the asteroid belt, and travel to other interstellar systems. It is unknown how much, if any, of this vision will be used in the final game.