As of next Tuesday, Halo: The Master Chief Collection will be just one game away from completion on PC. September 22 will see the launch of Halo 3: ODST for PC via Steam, the Windows 10 Store, and Xbox Game Pass—and, coupled with this launch, both the console and PC versions of the collection will be getting an expanded version of ODST's Firefight, the tough as hell co-op mode first introduced to Halo in the 2009 spin-off.
ODST, for those who have never played it, is a side-story set between events from the original Halo trilogy, told from the perspectives of a group of Orbital Shock Drop Troopers who arrive in New Mombasa just after the Master Chief's brief visit to Earth in Halo 2. In it, Bungie nudged some Halo mechanics back in the direction of Combat Evolved (health pick-ups, no dual wielding), introduced a between-mission hub world structure (perhaps a glimmer of what we'll see in Halo Infinite), and even weaved in an engaging radio play hidden across terminals in the game.
On Xbox One, ODST's full campaign was added to the collection in 2015, but it hasn't included Firefight. Earlier this summer, 343 announced that ODST Firefight would be added to both versions of the collection, and thanks to some early public testing we also know it'll support more customization options than the original version. You'll still be able to play classic Firefight (which was pretty challenging since the ODSTs are squishier than Spartans) or mess with the settings to add in helpful new additions like the Battle Rifle or even the Anti-Air Wraith tank.
The launch of ODST on PC will also mark the start of The Master Chief Collection's third season of unlockable content. This time around, the season unlocks will consist of brand-new weapon and character customization options for Halo 3's multiplayer, plus skins for ODST Firefight. Halo 3's multiplayer is also having a few ODST-exclusive weapons like the silenced SMG added to its sandbox.
After ODST, the only game left to be added to The Master Chief Collection on PC is 343's series debut Halo 4, which will likely launch within the next few months. That will almost get new PC players caught up on the mainline Halo series ahead of Halo Infinite's delayed release on Xbox One, Xbox Series X, and PC in 2021.