From Nintendo:
KEY INFORMATION
Get ready for an original game experience as players tilt Yoshi® through topsy-turvy worlds brimming with adventure.
* By tilting the Game Boy Advance SP, players will turn the environment around Yoshi to knock over enemies, swing pendulums, and help Yoshi run up walls and leap huge pits.
* All of Yoshi’s Island is trapped in a storybook, and only by meeting the challenges of each chapter will players succeed. Collect coins, defeat enemies or race for the finish to satisfy each course’s conditions.