Are Xbox 360 games be region-locked?
As per the usual for consoles (and unlike handhelds and the PC), 360 games are region locked. However, the region lock is at the discretion of the game publisher, and as such many titles publishes in other regions will work on a UK 360. There is no definitive list for these, but import sites such as Play-Asia will list whether the title is compatible with a UK 360.
