World 7 (Super Mario Bros. 2)
This world has only two levels instead of three. In the original story of Yume Kōjō: Doki Doki Panic, this is explained as the final page being the ending of the book that was torn out, which would have been the missing third level.
The level begins with the player having to climb a ladder. Instead of dodging Albatoss dropping Autobombs over blocks that blow up, creating pits, hitch a ride on the back of an Albatoss heading left. After jumping over multiple columns, the player will reach a plant, which, if plucked, will spawn a rocket which will take the player to the next area in the level. From here, the player will have to dodge Snifits, Shy Guys, Tweeters, and one Ninji to advance to the next area. This area involves climbing multiple ladders, dodging multiple Sparks, some Hoopsters, and another Snifit until reaching a door, which leads to the end of the level. Here the player fights Green Birdo.
7-2, the final stage of the game, takes place in a massive castle-like structure belonging to none other than Wart. This is the longest level in the game, and it features multiple encounters with Red Birdo. Also, it features a fight with Mask Gate at the end, which comes to life and attacks the player before allowing them to advance to the final room, where Wart is fought. The Mask Gate can be defeated by throwing the Mushroom Blocks in the room at it. Hitting it three times immobilizes the Mask Gate, allowing the player to enter it and head to Wart's room. Wart attacks the player by spitting bubbles. He must be defeated by throwing vegetables that come from the Dream Machine into his mouth, when he opens it to spit bubbles. Once this is done six times, Wart is defeated, and the innocent inhabitants of Subcon can be freed.