The greatest ninja-related game ever created.
"Dude what are you doing this weekend?" "Playing N+ at Frost's house, what else?"
N+ is a platformer in which you play as a small ninja and must traverse levels using your acrobatic skills. In order to complete a level you must collect a key and make it to the door before the timer runs out. Players can also collect gold pieces to add time. There is a free PC version along with XLA and PSP versions.
N+ is a great game, but the cause of much frustration.