360 games from a different region that are both backwards compatible and have a different set of achievements can be played on an XB1. I'm currently playing through the Japanese version of Gears 2. Clearing Horde on all the maps in the game will take a while. The Japanese version of Borderlands is also confirmed to work, and BioShock 1 & 2 are coming to BC and have multiple stacking regions as well. I didn't cross check the entire list maintained on Xbox Achievements to see what else works.