In his attempt to stop Bowser's mischief, Hongo the Great Book Spirit sealed him in a pop-up book, along with Yoshi's Island which is where Bowser was located at the time. The Spirit who loves Surprises showed up and told Yoshi the dinosaur there is a way to bring Yoshi's Island back.
It's up to Yoshi to save the day in Yoshi Topsy-Turvy. The game is divided into six chapters, each containing numerous stages. The player will have to tilt the world (using the tilt sensor) to help Yoshi climb walls, open new paths, and send enemies rolling away. Happiness Medals should be earned, allowing the player to move on to the next chapter if Yoshi successfully clears certain objectives that the Spirits ask of him. Along the way, Yoshi will be transformed into a ship, a ball, and a balloon.