Shadow the Hedgehog is a 2005 platform game developed by Sega Studios USA, the former United States division of Sonic Team, and published by Sega. It is a spin-off from the Sonic the Hedgehog series and follows Shadow the Hedgehog, a creation of Doctor Eggman's grandfather, Professor Gerald Robotnik, as he attempts to learn about his past while suffering from amnesia. Shadow the Hedgehog introduces third-person shooter elements and nonlinear gameplay to the Sonic franchise. To defeat enemies, Shadow can use various weapons and special attacks, and most levels have three possible missions that the player may choose to complete. The missions completed determine the game's plot and subsequently playable levels. The development team wanted to make a game featuring Shadow to capitalize on the character's popularity and resolve plot mysteries that began with his introduction in Sonic Adventure 2.