Aside from The Digital Messiah, and another potentially forthcoming User Error mission: Johnny LaRue, a map maker from the No One Lives Forever game community, is also working on a Single Player mission for TRON 2.0 called Abyss.

Sample Screenshots from Abyss


This expansion looks very promising. You can visit the author's home page to find out a bit more about Abyss, and his other map projects.