The story begins when Dr. Eggman uses the power of the Chaos Emeralds to unleash Dark Gaia, an ancient being that shatters the planet into pieces. During the attack, Sonic transforms into Werehog, gaining nighttime powers with elastic limbs and increased strength. With the help of Chip, a mysterious creature that accompanies him, Sonic travels to various regions of the world to restore the pieces of the planet and confront Dark Gaia.

• Day stages: Classic Sonic experience with fast platforming, boost mechanics, and 3D/2D transitions.

• Night stages: Sonic as Werehog engages in hand-to-hand combat, puzzles, and exploration, with a slower pace and emphasis on strength.