One Ups are the easily the most useful item in the game. However, since they are so useful, they should only be used at low health and/or low ammo, otherwise the effect is wasted. The maximum number of lives in the game is 9, so the extra life will be forfeit if the player already have 9 lives. The player should ensure that he gets them before he finishes the level, though, as they count toward the Treasure percentage. Failure to get all the One Ups will forfeit 10,000 points, even if all other treasure is obtained.