Sonic Unleashed is a Sonic the Hedgehog game to play in single player mode. The story begins with Dr. Robotnik trapped around a fleet of spaceships. While Sonic was turning into Super Sonic to stop his evil plan, Dr. Robotnik uses a new beam weapon to turn the Chaos Emeralds black so they become useless. After that, use the energy from the Emeralds to unleash a powerful monster, Dark Gaia. Dark Gaia is responsible for turning the earth into a wasteland. The beam gun produces a negative side effect on Sonic so that he turns into a Werehog. The Werehog is a type of creature that can possess great strength at night. Dr. Robotnik then pushed Sonic into space. Sonic safely landed on the planet along with the Emeralds.

Shortly after landing on this new stage, Sonic encounters a creature that has amnesia. Sonic believes that he is the cause of his illness, so he decided to help the creature discover his true identity. This creature later becomes Sonic’s companion and will serve as the player’s guide throughout the game. Later, Sonic names the creature Chip. As Sonic begins his search, he is accompanied by other friends, including Amy Rose and Tails. Sonic travels the world’s continents to help the creature discover who he really is. Having traveled across 6 continents, Chip finally remembered everything. Chip identified herself as Light Gaia, which is the opposite of Dark Gaia. For several million years, Dark Gaia had been pulling the planet apart, but Light Gaia would put it back together. Chip was released along with Dark Gaia.

However, due to Chip being released prematurely, his memory disappeared. Dr. Robotnik had ordered Dark Gaia to kill Sonic. Despite that, Dark Gaia powered up Sonic and absorbed all of his Werehog power so he could be cured of lycanthropy. Later, Light Gaia gives the Chaos Emeralds to Sonic so that Sonic can turn into Super Sonic and defeat Dark Gaia. Chip rescued Sonic by throwing him to the surface. After that, return to the interior of the planet. Before leaving, he gave Sonic his necklace and one last message. Sonic holds the necklace in his hand, speeds up with Tails and heads off to another new adventure.

There are various item boxes located throughout the game, including rings, shields, invincibility, and super shoes. Rings increase your life by 1-UP when you have collected 100 rings. Shields prevent you from losing the entire ring. When you are hit by an enemy, you will lose your shield. Invincibility protects you from losing Rings or death.