Tetris is a strange world (based very loosely on the game of the same name) on which everything is square-shaped, including the native residents. The world was formed by the Sacred Square - a source of enormous power, which the world hires guards to look after on shifts. Tetris is ruled over by Mayor Squaresly and nearly every day on the world is some sort of holiday. Being so far from the Palace of Power, Tetris never joined or participated in the war against Mother Brain.
- "The Trouble With Tetris" - Mother Brain and her henchmen discover the N Team has visited the world and finds out about the Sacred Square. Wanting this power, she sends her usual minions off to steal it. The N Team visits the world and meets Squaresly for the first time (who states no other non-square people have visited the world in a century), and is reunited with Prince Lyle, Princess Lana's clumsy brother who the world has employed as a guardian of the Sacred Square. Lyle has confidence issues and is unable to prevent the Sacred Square from being stolen, but with some help from Gameboy and the N Team, he becomes more confident and stops Mother Brain from getting back to Metroid with the Square. He opts to remain on Tetris, and help the world stand up to Mother Brain.
- "Totally Tetrisized" - Lyle has gone missing, so Mayor Squaresly calls the N Team back. A new villain, the Puzzle Wizard, has been taking over and turning the natives into Tetrads. After a lengthy trek (and Simon Belmont and Squaresly being turned into Tetris blocks in the process), they succeed in defeating the Wizard and freeing the world once again.