The Halo Master Chief Collection is also on sale for a fantastic $24.97 for Xbox on the Microsoft Store.
Definitely worth it if you have not got any or just one or two Halo games.
Yes, it is included in Gamepass but some of us like to buy games.
Plus, if you are going down the Gamepass route, get Ultimate and play on PC as well.
From the website:
Six games, one epic saga. The Master Chief's entire story is brought together and optimized for Xbox Series X|S. : Featuring Halo: Reach, Halo: Combat Evolved Anniversary, Halo 2: Anniversary, Halo 3, Halo 3: ODST Campaign, and Halo 4, this is the definitive Halo experience.