Shadow The Hedgehog is a video game for the Gamecube, PS2, and XBox that centers on Shadow trying to recover his memory, a goal he has been pursuing since he first appeared in Sonic Adventure 2. At the beginning of Sonic Adventure 2, his memory was incomplete, and after almost dying at the end of the game, he lost it completely. He continued to seek knowledge of his past in Sonic Heroes. In Shadow the Hedgehog a three-way war rages between the Black Arms, GUN, and Eggman, in which Shadow sometimes takes part while struggling to gather all of the 7 Chaos Emeralds, which he believes hold the key to his past. He finally regains his memory during his confrontation with Black Doom in the Last Story of the game. The game was developed in the United States.
The story begins with Shadow standing on a hill outside the city of Westopolis, thinking about Maria Robotnik, although he he doesnt know who she is (he says after the flashback, "And who's this Maria?"). After a flashback to the day she was killed, a gaping hole opens in the sky over Westopolis, and strange creatures ascend to Westopilis from it. He is then contacted by Black Doom, the leader of the creatures, the Black Arms, and tells Shadow to bring him the Chaos Emeralds "as promised." Torn between his desire to seek out his past, and to remain loyal to his promise to Maria, the player in the game decides the path Shadow takes by choosing which mission to complete in each stage. All of the story paths, however, are warped versions of the truth, but the true story of Shadow's past is told in the Last Story, which can only be unlocked by reaching all 10 endings of story mode.
In different missions, Shadow teams up with various allies, including Amy Rose, Charmy, Espio, Knuckles Knuckles, Maria, Rouge, Sonic the Hedgehog, Tails, Vector, Doom's Eye, E-123 Omega, and Dr. Eggman, who provide combat support and guidance. Anyone can grab a controller, connect to socket 2, and play a character as co-op (PS2 and Gamecube versions, not X-box). However this can't be done with Eggman, Doom's Eye, or Charmy, because they fly and do not attack. This is also the only game so far in which you can play as Maria.
The GUN enemies include human troops and robotic troops as well as traditional GUN Beatles and walkers.
The Black Arms include gun and sword wielding humanoid aliens, flying creatures, and missile-launching worms.
The Eggman Empire Enemies are Eggman's typical robots, including the Egg Pawns and bomb-throwing jugglers, as well as new Shadow Androids.