I will have to go with Tenchu: Stealth Assassins. Even in the title assassinS is plural... but in the first game it's single player. My friend Carlos and I played that game like it was going out of style. We wished that this game would have been and felt that it should have been created as a 2 player game. Because of some of the stealth issues... I can see why they went the single player route... but still!