Phantom Sonic (Sonic the Hedgehog)
Region-free. Will work on UK/EUR/US consoles.
This is one crazy game. It's essentially the first Sonic the Hedgehog, only insanely challenging which at the same time is great!
Levels start off nice and innocent, then it becomes possessed! ;) Enemies become tougher than the T800 Terminator and after a while, the Phantom Sonic starts to gradually catch up with you. If he touches you, you die and it's game over!
Makes for a great talking point and definitely would recommend Sonic fans to give this one a try.