World 3 (Paper Mario: The Thousand-Year Door)

World 3 is a level in Paper Mario: The Thousand-Year Door, played during the Bowser intermission following Chapter 6: 3 Days of Excess. Its name is denoted as World 3-X, with X being the number of attempts that Bowser has used for the level. Bowser has unlimited lives during this level. The music that plays during this level is an arrangement of the castle theme from Super Mario Bros.

Story
In Rogueport, Bowser laments about how he has been unable to find any Crystal Stars or Princess Peach, until Kammy Koopa arrives and tells Bowser that Magikoopa scouts have found a suspicious underground chamber not on any maps. With the Hammer Bros. battalion unable to breach the chamber, Bowser goes to the chamber to do so himself, after which he enters World 3. The chamber leads to Rawk Hawk's training room, where Rawk Hawk refers to the chamber as his Secret Training Facility, claiming that he imported the X-Nauts "to up the difficulty level".

Layout
This level is modeled after the castle levels from Super Mario Bros. Bowser starts in a corridor with several Fire Bars, which can be destroyed by holding to breathe fire, and two pits of lava, followed by a yellow block containing Meat and three X-Nauts on a bridge made of Brick Blocks. Following these obstacles is a split pathway separated by indestructible stone blocks, with a long Fire Bar in the middle. Bowser can only access the bottom pathway, which contains several coins, if he intentionally takes one or more hits to shrink to an extremely small size. The bottom pathway also features another yellow block; however, because Bowser is extremely small, it cannot be destroyed. After this, an X-Naut PhD who throws explosive potions at Bowser appears on a yellow block; it is automatically defeated if Bowser destroys the yellow block, which also contains Meat. Finally, the rightmost area of the level's castle section contains a jump pad, which Bowser must use to ascend to a small overworld area with a staircase made of Brick Blocks, a single X-Naut, and the flagpole. To the right of this jump pad is a Warp Pipe on a platform high above the floor; however, this Warp Pipe is non-functional.