World Mushroom is the first special world in New Super Mario Bros. 2. This world has a generic design which is similar to that of World Flower and World Star. The background colour of this world is pink. It is an alternative world to World 2 and thus it is optional. This world can be accessed by completing World 1-Cannon. There are three Toad Houses in this world, one of each of red, green and yellow (Star) varieties.
There are nine levels in this world and, unlike normal worlds, does not have a tower level. There is also only three normal levels on the main path in this world, contradictory to the five-to-six levels found in normal worlds. Levels in this world (other than World Mushroom-Rainbow and World Mushroom-Cannon) can be based on any theme. There is also a Ghost House in this world. There are also two secret levels which the players have to find the secret exits for. The world ends, as always, with the castle level, where Larry Koopa, the boss of this world, is waiting, unless the player takes the path to the cannon, which will lead to World Flower when completed, allowing the player to skip an additional two worlds, World 3 and World 4.
 Enemies introduced
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