Sonic Unleashed is backward compatible and even features FPS Boost on Series X, making it the most stable official way to play.
The search for a "new" Sonic unleashed experience often leads players to the modding community. While the base ROM remains the same, several modern patches have breathed new life into the game: sonic unleashed rom download new xbox 360
If using an emulator, look for "patch" files to disable motion blur or fix lighting bugs. Sonic Unleashed is backward compatible and even features