Developers from 343 Industries have announced the full release of Halo 3: ODST. The game will hit Steam, Microsoft Store and Xbox Game Pass on September 22nd, one month after the beta.
The game will be included in the collection of the series called The Master Chief Collection. Purchasing this set, you get: Halo: Combat Evolved, Halo 2, Halo 3, Halo 3: Halo 4 ODST, and Halo: Reach. The fifth part, called Halo 5: Guardians, is not included there yet.