There’s a tool to check what games are registered on Steam. Well, it’s mostly reliable and has leaked many games coming to the service. Furthermore, it looks like there are plenty of new games that could be heading to Steam. People normally use this tool to peek into the Steam database.
Halo 3 has also been discovered in the database which could mean, Microsoft will start releasing older Xbox 360 games published by Microsoft Game Studios on PC, or Valve is adding support for Steam Community hubs for non-Steam games.
Here’s the listing for Halo 3 (via NeoGAF). You can find the complete list of all the games that have been found so far below, and plenty of them are already confirmed to be heading to Steam. Games like Fez are obvious because if you’re going to release it on the PS3, it should also be released on the PC.
Octodad: Dadliest Catch Beta
Duke Nukem 3D: Atomic Edition (Duke Nukem 3D+)
Super House of Dead Ninjas
LucasArts Test App
Fast and Furious 6
Cut the Rope
Shadow Warrior Complete
THE KING OF FIGHTERS XIII
Resident Evil: Revelations
THE KING OF FIGHTERS 2002 UNLIMITED MATCH
THE KING OF FIGHTERS ’98 ULTIMATE MATCH
Quantum Conundrum 2
Halo: Combat Evolved
Angry Birds Space
Angry Birds Seasons
Halo 3 for PC? I would buy it DAY1!