Sonic the Hedgehog is Sonic's first appearance on the PS3 and Xbox 360 in an all-new adventure, this time in the human world. Sonic meets Elise, the princess of Soleanna, which he quickly makes friends with. Unfortunately, Dr. Eggman quickly intervenes and kidnaps Elise in order to destroy the kingdom of Soleanna and its up to Sonic to rescue her.

A line-up of characters from previous games make their returns including Tails, Knuckles, Shadow and a brand new character, Silver the Hedgehog. Sonic races through stages with blinding speed using the 3D elements similar to the Sonic Adventure games. Along with new gameplay elements, familiar features make a return. The gameplay is split up in action stages, fast levels with alternate pathways, and free-roaming town stages where the characters can explore the towns, talk to other characters, get new quests, and visit the shops, similar to the Adventure Fields from Sonic Adventure.

During the game, three main characters can be controlled: Sonic, Shadow and Silver. There are 11 stages in total, and they are tweaked to the abilities for each of the characters. Sonic is the only one to have access to super speed stages, and he has custom abilities, such as the spin dash, light dash, homing attack, bounce attack, a sliding kick, a tornado kick, a mach speed dash and grinding. These are acquired in exchange for rings in stores. Sonic can also trade gems for special powers. Shadow's abilities are largely derived from Shadow the Hedgehog, with a focus on driving vehicles such as buggies, hovers, bikes and gliders. There are also various melee attacks, similar to those of Sonic, but Shadow does not use firearms in this game. The new character, Silver, is a time-traveling hedgehog. His main means of attack are psychokinetic powers. He can pick up and throw objects, and levitate. Additional abilities can be purchased in the in-game stores in exchange for rings.

For certain missions, you take control of an amigo, automatically assigned in specific stages. Sonic gets the help from Tails and Knuckles the Echidna, Shadow's sidekicks are Rouge the Bat and E-123 Omega, and Silver is assisted by Blaze the Cat and Amy Rose.

There are two multiplayer modes: Tag Mode (co-op) and Battle Mode (versus in a race for gold medals). The characters are voiced by the cast of the Sonic X animated TV series.