First and foremost, Halo 3: ODST is out now on PC–you can grab it on Steam, the Microsoft Store, or Xbox Game Pass for PC. It’s the fifth game in the package to come to PC, following Halo: Reach, Halo: Combat Evolved, Halo 2, and Halo 3. The sixth game in the package, Halo 4, will be released at some point later in 2020.
ODST was already available for MCC on Xbox One, but the big update introduces ODST Firefight on console. Some of the notable updates for ODST Firefight, which is available for PC and Xbox One, are new weapons in the form of the Halo 3 battle rifle and ODST’s assault rifle, as well as the Hornet and Anti-Air Wraith vehicles, among other things.