Halo CEA, Halo 3, Halo 3 ODST, and Halo Reach all coming to Backwards Compatibility soon, All Xbox 360 Halo DLC Free, Halo 5 4K on Xbox One X, and Halo Wars 2 Seasons Pass DLC Revealed!

Source(s):

Halo Community Update https://www.halowaypoint.com/en-us/news/halo-summer-celebration

Halo CE Anniversary, Halo 3, Halo 3 ODST, Halo 4 Backwards Compatibility https://news.xbox.com/2017/07/06/halo-summer-celebration/

Halo 5 Solo Queue Update https://www.halowaypoint.com/en-us/news/july-august-2017-season

Halo Xbox 360 Map Packs – Free Download https://www.reddit.com/r/halo/comments/6lobhi/halo_xbox_360_map_packs_free_downloads_available/