Time Limit

A Time Limit is instituted in many Mario series games, especially early platformers.

Time Limit in Platformers
All the Super Mario Bros. series (not including the Doki Doki Panic rip-off US version of Super Mario Bros. 2), Super Mario World, and even New Super Mario Bros. have time limits in most levels, that is, a certain amount of seconds to find the level exit (or a secret exit in the case of World). These limits usually start large (300/400 seconds), but are no less than 200 seconds and are used as a means to keep the Player moving throughout the level, and not have a luxury of "waiting" for enemies to clear on their own by falling down a pit, for example. Faster music cuing the player to finish up the level occurs often if there are less than 100 seconds left. Also, when a level is finished successfully, the time left is multiplied by a certain number, varying by game (often 50), and added to the player's score.

However, levels are designed in such a way that they can be beaten well before the time limit expires. If it does expire on a tortoise-moving player, a life will automatically be lost. Strangely, if the player starts at a midway point in a level after dying, the time resets all the way back up to the original starting time, making it easier to complete.