My vote is definetely for Resident Evil 4 (GCN) just for being the best game the survival/horror genre's ever seen and revolutionizing the way a game progesses its storyline. Amazing is too small a word. Another strong competitor would be God of War (PS2) along with Shadow of the Colossus. The year isn't over so there is still room for a masterpiece to fall. Maybe a 360 game has a chance.