It seems the good old days of Halo 3 custom games are really coming to an end. Microsoft and 343 Industries have announced that they will shut down online services for “legacy Halo Xbox 360 titles” on December 2021. This will affect all Halo games that were released on the Xbox 360, including the original Halo Wars and Spartan Assault.
All of the Halo Xbox 360 games you already own are still going to be playable indefinitely, obviously. However, digital sales are already being discontinued, and several online features such as online matchmaking will be limited or straight-up disabled when the time comes. You can read the detail on which online features will be affected on the chart below. Items with a green checkmark indicate no change, while a red X is for features that will no longer be available late next year. Achievements and Avatar awards that require online matchmaking and challenges will also no longer be obtainable.
Other things to note: this shut down will affect backward compatibility versions via Xbox One and Xbox Series X since it still relies on legacy Xbox 360 servers. But, Halo Wars: Definitive Edition and Halo: The Master Chief Collection will not be impacted since their servers are designed for PC as well as current and next-gen consoles in the first place.
