Sonic's first outing on the Nintendo DS system features action in two screens with a story featuring Sonic getting involved in another one of Dr. Eggman's evil plots. A mysterious Emerald is left behind by Dr. Eggman, but an unfamiliar character makes off with it before Sonic can investigate! Sonic gives chase, and thus the adventure begins.
Playable characters in the game are Sonic the Hedgehog and new character Blaze the Cat. Appearances from other character include Miles "Tails" Prower, Amy Rose, Cream the Rabbit, and Knuckles the Echidna. Each playable character has four moves as well as a variety of "Trick actions" which, when performed, will raise your Tension Gauge. Filling the gauge allows you to do a Boost which will propel Sonic or Blaze at a high speed across the ground or along the air to defeat enemies or move certain blocks.
There are 14 levels that play out over both the top and bottom DS screens, giving you a bigger view of your surroundings. You will race through the levels collecting rings, using "gimmicks" such as bungee ropes and giant waterwheels, performing tricks, collecting power-ups, and defeating enemies. When you beat each level, or "act", you will face a Boss Act which is played out over the top screen in 3D. In addition to these levels, there are Special Stages. These are played on the touch screen, and unlike the rest of the game, feature control with the stylus.
Upon completion of the game, Time Attack mode will be available. In it, you play levels/boss acts for the best time record. Battle Play is a multiplayer mode in which two players compete to finish a level first. It can be played over single-card download or multi-card wireless.