Both Halo: Combat Evolved and Halo 2 eventually found their way onto PC, but it doesn’t look like other Halo titles will be joining them.
Recently, the latest AMD beta drivers apparently had an entry for Halo 3, which of course sparked speculation and rumors that the game will come to PC a full six years after its original release on Xbox 360. It would make sense to have the full Halo trilogy available for PC owners. However, this isn’t going to happen.
Microsoft recently explained the situation to Eurogamer : “We currently do not have plans to release any Halo titles on Steam, nor do we currently have plans to release a PC version of Halo 3.” While it’s not a never, it’s a definite “no, not right now.”