The beauty of Xbox One backwards compatibility is in its simplicity. If you own any supported Xbox 360 games either on a physical disc or digitally, you can play them again on your Xbox One. For
Because there was no backwards compatible version of the game with the One and Series X/S, they didn't add it to the 360 store, because people don't buy as many games in the 360 store as they do in the One store, it didn't come back on the PlayStation 3 PSN , because PSN closed, it only came back on STEAM because the PC doesn't have this Playing Sonic Generations, one of my favorite 360 games, on the Series X when I got one last December was a crazy experience. It was a night and day difference and shows what a great feature backwards compatibility is and what a strength it can be for the console this gen if some more Xbox/X360 classics can be added to the program some day. 2Left 4 Dead 1 AND 2 are backwards compatible, along with the orange box. The rest arent back compat for various reasons, like the team at Xbox just not being able to have them in a playable state, or license issues preventing games from being brought forward.