The basic gameplay in The Lost Levels is largely similar to Super Mario Bros., with the game divided into thirteen new worlds (Worlds 1-9 and then Worlds A-D), with each world then divided into four levels. The fourth level in each world takes place inside of a castle, where Mario (or Luigi) must fight either a False Bowser or the real one. Upon his defeat, which is done by jumping over or running under him and touching the axe, will send the player to the next world. If it's the last world, the player will rescue Princess Toadstool and the game will be over.
While the basic gameplay was similar to the very first game, there were plenty of little changes here and there that made it different. The items/abilities from the first game returned, but a new item was introduced, the Poison Mushroom. This item functions similar to Mario hitting an enemy or obstacle, although it disappears when touched.
Enemies also behave differently in The Lost Levels when compared to the first game. Bloopers, for example, can be found outside of underwater levels and other enemies, such as Koopa Troopas, can even be found underwater. One new enemy was added, which is the red Piranha Plant, which move faster and do not hide when standing next to pipes, although they do when standing on top of a pipe.
Super Mario All-Stars
The version of The Lost Levels included in Super Mario All-Stars made a few changes to the base game. One example is an update to the graphics engine, which featured 16-bit graphics compared to the 8-bit in the original. The game also made it easier to unlock the A-D stages of the game, which required the player to beat the game a total of eight times in the original Japanese version (the player only needed to beat the game once in All-Stars).