 Sonic Unleashed , released as Sonic World Adventure ( Japanese : ソニックワールドアドベンチャー , Hepburn : Sonikku Wārudo Adobenchā ) in Japan , is a 2008 video game in the Sonic the Hedgehog series developed by Sonic Team and published by Sega for multiple platforms in 2008 . The game follows Sonic the Hedgehog as he attempts to restore the world to normal after his nemesis Doctor Robotnik ( Eggman in Japan ) uses a Chaos Emerald to turn the world into a nightmare realm. Einzeln wurde das Spiel für die PlayStation 2, Wii, Nintendo DS und Xbox 360 veröffentlicht, sowie für die PlayStation 