Halo has for the most part been a Console exclusive game. The release of the first on PC, was just a ploy to get folks like me hooked on the series. The only reason Halo 2 was released on PC was to get a new generation moved over to Vista, thus the reason it's Vista only.
The new updates that are making the Xbox One backwards compatible with older, popular Xbox 360 games and incorporating the ability to use keyboard and mouse on some games pretty much guarantees that most new Xbox releases will remain exclusive to the console.
Last edited by Trail_Mystic; 11/22/15 03:29 AM. Reason: Should have been Halo 2 not 3 in my first paragraph.