A lot of map packs.
Microsoft and 343 Industries announced a “summer celebration” for the Halo franchise this week, including new merchandise and a 4K update for Halo 5: Guardians alongside the Xbox One X launch this November.
343 Industries also announced that Halo 3, Halo 3: ODST, Halo 4, and Halo: CE Anniversary would be coming to Xbox One backward compatibility later this year. The four Xbox 360 titles join Halo: Reach and Halo Wars, which became backward compatible with the Xbox One in November 2015.
Additionally, “every Xbox 360 Halo add-on map pack” would become free on the Xbox Store permanently. The list of add-ons made free today include:
- Halo 3 Legendary Map Pack
- Halo 3 Mythic Map Pack
- Halo 3 Mythic II Map Pack
- Halo Wars Historical Battle Map Pack Add-On
- Halo Wars Strategic Options Add-On Pack
- Halo: Reach – Anniversary Map Pack
- Halo: Reach – Defiant Map Pack
- Halo 4 Champions Bundle
- Halo 4 War Games Map Pass
The only add-on not currently available for free is the Noble Map Pack for Halo: Reach, which should be fixed in the near future. Other events for Halo’s summer celebration are a planned Halo 3 throwback playlist in Halo 5: Guardians for the 10th anniversary of Halo 3, various community events, and more listed at Halo Waypoint.