https://wccftech.com/halo-the-master-chief-collection-game-pass/

During today’s special Gamescom 2018 Inside Xbox live stream, Microsoft announced that Halo: The Master Chief Collection will be available as part of the Xbox Game Pass subscription from September 1st.

At the same time, the game will also be enhanced for the Xbox One X console and received the improvements that have been under testing via the Insider Program.