The core gameplay of Sonic DS was to rub the bar on the touch screen as fast as possible. The fast you rub, the fast Sonic goes. There also seems to be some sort of obstacle jumping element. In the end, the whole idea was scrapped for the 2D platformer, Sonic Rush. Playable characters in Sonic DS included Sonic, Tails, Knuckles, Amy, Cream, Shadow, and Blaze.