Microsoft is already planning for certain other Halo and Xbox-related anniversaries, but right now, the focus is on the Xbox 360 classic Halo 3: ODST.
Believe it or not, but it's now been 15 years since we dropped into New Mombasa as a rookie on a mission to locate Alpha-Nine. This also includes the debut of the wave-based cooperative mode Firefight. The official Halo social account has taken a moment to celebrate this with an extended clip featuring some gameplay.
If you do want to relive this unique noir-like release, you can check it out in the Halo: Master Chief Collection. It also offers multiplayer support. Although it did things a bit differently, this outing - which was one of Bungie's final Halo games, was generally well-received by fans.