In a surprise move, Disney Games has begun releasing their catalog of games on Steam, recently. Among the titles available there, that will be of particular interest to fans of TRON, are
TRON Evolution and
TRON 2.0.
TRON Evolution was released first, on October 6, 2014. TRON 2.0 followed a few days later, on October 10, 2014. (During an AMA session on Reddit, representatives of Disney Games were bombarded with requests for TRON 2.0 after TRON Evolution appeared, so they decided to add it to Steam as well.)
The Steam release of TRON Evolution is practically indentical to the Retail DVD PC version, still using Games for Windows Live for online Multiplayer and achievements.
You can share your thoughts about the Steam release of TRON Evolution, in this I/O Forum topic here on TRON-Sector.
The Steam version of TRON 2.0 is also identical to the Retail CD/DVD PC version, with the Official v1.042 Patch pre-applied. But online Multiplayer is broken, due to the fact that the GameSpy service the game relied on has since shut down.
However, the TRON 2.0: Killer App Mod fixes the broken Multiplayer, so it functions again. It also adds widescreen support to the game, and numerous other improvements.
You can find out more about the mod, and share your thoughts about about the Steam release of TRON 2.0, in this I/O Forum topic here on TRON-Sector.
02/24/2015 UPDATE: Both TRON Evolution and TRON 2.0 are on sale on Steam at 50% off, until Mar. 2, 2015.