Storyline
The story of Ground Control II takes place in that same universe as that of the original game but starts 320 years later and has little in common with the original game.
In the fictional universe of the game, the human race has discovered faster than light travel and has colonized the galaxy. There are two groups of colonies in this universe, dubbed the Inner Sphere and Outer Sphere. A fictional physical phenomenon causes the communications between the two area to be only possible through a network of special relay stations built at the border of the spheres. Intergalactic travel is also impossible due to a fictional unexplained barrier between the galaxies.
Read more about this topic: Ground Control II: Operation Exodus