The world is in peril as forces, both good and evil, make a play for the powerful Chaos Emeralds. In Shadow the Hedgehog, you can control Shadow and choose which side to fight for. This 3D platformer lets you use weapons, vehicles, environmental objects, and time and space manipulation to combat your foes. Although it is a 3D platform game as with the more recent Sonic Adventure games, the game's levels each feature up to three different missions (Hero, Dark, Normal) that the player may choose to complete. The game's plot depends on which mission is completed as well as subsequent playable levels. The game stars Shadow the Hedgehog and his quest to recover his memory, a goal he has been pursuing since his debut in Sonic Adventure 2, while an evil alien race known as the Black Arms is invading the planet.