The game follows Sonic the Hedgehog as he attempts to restore the world to normal after his nemesis, Doctor Eggman, splits the world's continents into pieces with a powerful new ray weapon and the power of the Chaos Emeralds, as well as his struggles with his new beast form generated by the corrupted Emeralds, Sonic the Werehog.
Daytime gameplay consists primarily of behind-the-back, third-person stages with seamless shifts to 2D side-scrolling platform gameplay. Concepts returning from past games include Sonic's trademark high-speed gameplay, as well as improved lock-on for automatically targeting and hitting enemies.
During night sections which, under normal gameplay circumstances, make up around 40% of the game, Sonic transforms to his alternate Werehog form. The gameplay shifts from fast-paced action to a slower, solely 3D, hack and slash style of gameplay. The Werehog form allows Sonic a great deal of strength, and gameplay involves smashing enemies and destructible environments, whilst his stretchable arms will allow him to reach high platforms and perform special attacks.