Sonic Boom is a total modification of Sonic 2, created by snkenjoi and ionjnekns, along with a wide array of talented contributors.
It's quite a short game at under 10 minutes, but it's worth the play!
Check out the gameplay here: https://www.youtube.com/watch?v=9ECvdnHdXTc
Region-free. Will work on UK/EUR/US consoles.