Sonic Unleashed features Sonic the Hedgehog as he battles to restore the world after it’s shattered by the evil Dark Gaia. The game introduces a day-night cycle with Sonic transforming into a powerful Werehog at night, offering different gameplay styles: fast-paced day levels and slower, combat-focused night levels. The story unfolds through various global locations, each with unique environments and challenges. The game combines classic Sonic speed with new gameplay mechanics, and is known for its vibrant graphics and ambitious design.