Halo 3: ODST and Halo: Reach were not released alongside the original Halo: The Master Chief Collection (MCC) in 2014. Because they were released later and can be bought separately, there are some situations where someone can own Halo: MCC but not have access to the campaigns and firefight mode for Halo 3: ODST or Halo: Reach.
Some Xbox Game Pass players have full access to every Halo game within Halo: MCC while they are subscribed. You can check the Halo: The Master Chief Collection page on the Xbox Store to see which Game Passes it's available on.
For those who purchased Halo: MCC separately, here's the full breakdown:
Halo 3: ODST
Campaign and Firefight
- Xbox One: Not included originally in Halo: MCC, but available as a separate purchase.
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PC: Included in Halo: MCC or available as a separate purchase.
- No separate purchase needed if you already own Halo: MCC on PC.
Halo: Reach
Campaign and Firefight
- Xbox One: Not included originally in Halo: MCC, but available as a separate purchase.
-
PC: Included in Halo: MCC or available as a separate purchase.
- No separate purchase needed if you already own Halo: MCC on PC.
Multiplayer
- Xbox One: Included in Halo: MCC for free, or included with a separate purchase of Halo: Reach.
-
PC: Included in Halo: MCC or available as a separate purchase.
- No separate purchase needed if you already own Halo: MCC on PC.