https://www.overclock3d.net/news/software/halo_3_odst_is_now_available_on_pc/1
 
Microsoft has announced that Halo 3: ODST is now available for PC, releasing as part of The Master Chief Collection. Now, Halo 3: ODST is available on Steam, the Microsoft Store and through Xbox Game Pass for PC. On PC, Halo ODST will support 4K resolutions, Ultrawide displays, 60+ FPS framerates and support graphical settings which go beyond what was available with the game's original Xbox release. FOV customisation, mouse/keyboard support and more will help further differentiate this game from its original Xbox 360 release. 

With this release, Halo 3: ODST's Firefight mode is now available as part of Halo: The Master Chief Collection on all platforms, enabling 4-player co-op on dedicated servers across ten legacy maps. Halo 4 will be the next game to arrive as part of Halo: The Master Chief Collection, after which, Halo 5: Guardians will be the only Halo title to lack a PC release. At this time, Microsoft has not revealed any official plans to bring Halo 5 to PC. 
 
Well it makes sense in my opinion that to make more money you need to support all gaming platforms. 

🎶Woah ah ah ah ah oh ahhhhhh.....ahh has ahhhh ah ah ah.....🎶

I was all hyped for the MC on PC, but i've hardly touched it. :( 

I haven't played a halo game since the xbox 360 was relevant.

ODST is really underrated in my opinion, the score in it is one of my favourites in the Halo series. Can't wait to get a 3090 and finally get around to playing all of them again.