Yea, I need to update that doc.
GalCiv III (And in the future IV) use the "Galactic" engine. It's specially made for "massive scale" 4X games. The focus is on doing as much in parallel as possible so that we can have big galaxies with lots of players.
The main limitation on GalCiv is that the player turns are sequential (player 1, player 2, etc.). I am hoping we can come up with a way for players to be able to move simultaneously provided that they aren't in the same general location which would greatly speed things up.
Nitrous is the basis of all our new titles. For the way we use Nitrous, it could almost be described as a technology as Stardock, during the development of Star Control, created a game engine on it called Cider.
Nitrous handles the rendering, I/O, and task scheduling while Cider handles everything else (UI, Audio, Data management, scripting, physics, animation, etc.).
So an updated chart would have Nitrous-->Cider. Cider is based on Nitrous. Since Nitrous is made by our partner, Oxide, we can't very well call our work Nitrous v2.0 hence the name "Cider".