The Dead Lords were defeated and exiled by Arnor, a civilization that has now completely vanished. An expedition force of the Terran Alliance discovers the last survivor. He explains that the civilization's power is to be found in a number of shards shattered across the galaxy. To completely free the galaxy of the Dread Lords, the Terran Alliance must locate these shards and destroy them. In Twilight of the Arnor players can take on the campaign concludes the fate of both the Dread Lords and the Arnorians.
The second expansion pack to Galactic Civilizations II: Dread Lords adds a lot of game enhancing features, a new campaign concluding the Dread Lords trilogy and gives every civilization its own unique technology tree: unique ships, unique planetary improvements, unique starbases and more. It also introduces a new victory condition option called Ascension. Some game-engine enhancements reduce the memory and hardware requirements while Twilight aims to offer better graphics.