In addition to Xbox One games, a limited number of Xbox 360 titles will look better on Xbox One X. After announcing four Xbox 360 titles that will be enhanced on Xbox One X back in October, Microsoft today confirmed three more--and they are some good ones.
Skate 3, Mirror's Edge, and Gears of War 3 are joining Assassin's Creed, The Elder Scrolls IV: Oblivion, Fallout 3, and Halo 3. So there will be a total of seven backwards-compatible titles. It's not immediately clear if the three newly confirmed titles will be enhanced on Xbox One X from the start or if that will happen later. We also don't know the specifics about how they are being enhanced for the new console.
For the four previously announced games, Microsoft said they will run in a "higher resolution, 9X the original pixel count, and [with] expanded color details," according to Microsoft. This is done using the Heutchy Method--named after the Microsoft engineer who developed it--which is also used to play improved versions of original Xbox games on Xbox One.
This "leverages the power of Xbox One X to let the Xbox 360 emulator present the very best version of the game possible with the existing assets--all without touching the game code."