Sometimes game worlds are created for the game. The result is a game that can feel a bit lacking in the soul department. GalCiv I, to some of us felt a bit light on the soul side. It was focused largely on just moving units and research technologies and the actual civiliziations were just a bunch of interchangeable names.
Ironcially, the game back story has been in development for nearly two decades. When the game was originally developed for IBM's OS/2 operating system in 1993, the game tapped a series of sci-fi stories. That is where the Drengin and the Torians and the Arceans all came from.
To put it all together and explain the back story and the place where the humans fit in, I've finally put together the Databank entry on the GalCiv universe.
If you're interested in how the backstory has evolved and changed over the years, check it out.