Whilst incorporating Sonic's traditional platforming and trademark speed, the gameplay style for this game is notably different, focusing on 2D side-scrolling platform gameplay rendered with 3D visuals, as well as behind-the-back, third-person stages; gameplay seamlessly transitions between these two styles. This radical change in gameplay, coupled with the focus on extreme speed and boosting (during the day stages), makes this game considered partially the first "boost 3D" Sonic game, due to its style that was later represented in Sonic Colors, Sonic Generations, Sonic Forces and, partially, Sonic Lost World.
Gameplay primarily consists of two modes. The first is 2D side-scrolling platform gameplay, rendered with 3D visuals (as found in the Sonic Rush and Sonic Rivals series), with seamless shifts to behind-the-back, third-person stages. Concepts returning from past games include Sonic's trademark high-speed gameplay, as well as improved lock-on for automatically targeting and hitting enemies. In the 2D gameplay, sliding across the ground also returns, and a new feature, "Drift" allows Sonic to slide around a corner at high speed. Players will also be able to perform a new side-step maneuver known as "Quick Step", allowing Sonic to instantly dodge obstacles to the left or right. As the player goes through the game and Sonic gains more Experience Points, the player is able to upgrade and gain new abilities for Sonic and Sonic the Werehog.
An on-screen Ring Energy meter can be filled by collecting rings, which is used to activate a temporary speed increase known as Sonic Boost, during which time the camera uses a fish-eye effect and motion blur; hitting enemies and obstacles will reduce the meter. Action Chaining allows the player to collect energy more quickly, by collecting rings faster or by stringing together sets of actions, including button input sequences, some of which will be in midair. Repeated action chains will allow the player to perform special moves or access different routes in the level. Shield pick-ups from previous games will make a return, protecting Sonic from various hazards.
The second is 3D beat-em-up style gameplay with platforming and puzzles thrown in. During night sections of the game, Sonic transforms to his alternate Werehog form, and gameplay shifts from fast-paced action to a slower, more platform-oriented style of gameplay. The Werehog form allows Sonic a great deal of strength, and gameplay involves smashing enemies and destructible environments, whilst his stretchy arms will allow him to reach high platforms and perform special attacks. Completing Real-Time Interactions on weakened enemies in the PlayStation 3/Xbox 360 version grants the player a Critical Attack bonus. The Ring Energy meter changes to two bars, Unleashed and Vitality; the Vitality Bar acts as a health bar and replenishes by collecting rings, whilst the Unleashed Bar activates with a button to increase attack strength, decrease vitality loss from enemy attacks, and enables special moves, and replenishes by defeating enemies and destroying objects.
- Apotos / Windmill Isle
- Spagonia / Rooftop Run
- Mazuri / Savannah Citadel
- Holoska / Cool Edge
- Chun-nan / Dragon Road
- Shamar / Arid Sands
- Empire City / Skyscraper Scamper
- Adabat / Jungle Joyride
- Eggmanland / Eggmanland
- Jason Griffith as Sonic the Hedgehog / Sonic the Werehog
- Amy Palant as Miles "Tails" Prower
- Lisa Ortiz as Amy Rose
- Tony Salerno as Chip Light Gaia
- Dan Green as Professor Pickle
- Christopher Collet as SA-55
- Mike Pollock as Dr. Eggman