[UPDATE 2016-03-29] The game is now available to all Xbox One owners.
Those gamers lucky enough to be in the Xbox One Preview and testing the next system update will have a little exclusive for the time being and find that the Xbox 360 RTS Halo Wars is now backward compatible.
Released in 2009, the game was set long before Halo: Combat Evolved and told a story of a new group of soldiers and their dealings with the Covenant. The game was lauded for its controls that were designed for making the most of the 360 controller.
Cinematics in the game are from Blur Studio and were so good at the time that whenever they were working on new stuff for Halo, fans would be asking the question “so, when are they making the movie?”.
For the latest list of backwards compatible titles (available to all Xbox One owners), check out this page on Major Nelson’s site.