It appears Microsoft technically wasn’t lying when it stated that the May 29 release date for Halo 3: ODST on Xbox One was simply a placeholder — the game actually released one day later, available as a free download for all early purchasers of Halo: The Master Chief Collection.
Anyone who played Halo: The Master Chief Collection online between its November 11 launch and December 19 should have received a message on Xbox Live with a voucher to download the ODST campaign. The message will disappear after June 30, but Microsoft stresses that users can still receive the content by contacting Xbox support after this time. The download is hefty, weighing in at over 8 gigabytes, and it’s only playable via Master Chief Collection. If you waited for the game to fix the matchmaking woes that led to ODST’s inclusion in the first place, it will also be available as DLC for $5.
Much like the main four Halo games included in The Master Chief Collection, ODST includes its own playlists and challenges, and it also supports unified control schemes to stop you from throwing a grenade when you want to hit the melee button for the thirteenth time. However, only the campaign for the game was included: the popular “Firefight” mode has been omitted, most likely because ODSTs campaign was offered primarily as damage control.
Also included in a free content update for The Master Chief Collection is the multiplayer map “Remnant,” a remake of Halo 2’s “Relic.” Unlike ODST, there are no eligibility requirements to download the map; just update your game and it will be added to the Halo 2: Anniversary playlist. The update also brings with it new achievements, “improved stability” across multiple areas, and “improved skill matchmaking for parties in ranked playlists.”