Shadow the Hedgehog is a platform game that incorporates elements from the third-person shooter genre and elements from the action-adventure genre. Like previous games in the Sonic series, basic gameplay involves running quickly, collecting rings, tricky platforming and destroying enemies.[2][3] Shadow collects rings as a form of health; when he is attacked by an enemy or takes damage from the environment, ten of his rings bounce away from and form into a circle around him. When Shadow has no rings and takes damage from an enemy he dies, loses a life and goes back to the last checkpoint, which also serve as teleportation devices, allowing Shadow to return to different sections of the current level.[4] Each level is completed by undertaking a mission, and each mission is labelled "Hero," "Dark," or "Normal".[5] The "Hero" missions involve completing tasks for the Sonic series' heroic characters, or Doctor Eggman on one occasion,[6] and the "Dark" missions involve completing tasks for either Black Doom or Doctor Eggman. The "Normal" missions involve reaching the Chaos Emerald or Goal Ring at the end of the stage.[5] Examples of non-neutral mission objectives include killing all enemies in the stages, destroying an aircraft flying to the end of the level, or activating or destroying objects in the stage.[7] All enemies attack Shadow regardless of the mission chosen.[3][4] The mission types selected affect the plot, the levels played, and the ending received out of ten possibilities.[5][8] Each level features cutscenes that advance the story, and seven levels also feature boss battles.[9] There are 326 possible paths to take in Shadow the Hedgehog, and each pathway is individually named.[10]
Shadow uses a submachine gun to shoot a GUN soldier. The game's mature themes and its addition of guns were two major areas of criticism.
New gameplay features distinguish Shadow the Hedgehog from previous Sonic games. For example, Shadow can pick up and use guns to fight enemies.[4] Parts of the scenery, like traffic signs, can also be used as weapons.[5] Another new feature is the ability to drive vehicles, such as motorcycles and an alien aircraft.[2][4] Although Shadow can outrun the game's vehicles, the latter have unique capabilities, such as crushing enemies and traversing otherwise impassable acid-covered areas.[9]
As in most Sonic series games, the Chaos Emeralds play a major role; they help Shadow remember his past[11] and allow him to perform Chaos Control and Chaos Blast. Chaos Control allows Shadow to move more quickly in levels and slows time in boss battles, and Chaos Blast creates an explosion that destroys or severely damages all nearby enemies. Shadow can perform Chaos Control after the player fills the Hero Gauge by defeating Black Arms soldiers (or by doing other heroic acts such as; putting out fires and healing wounded soldiers), and he can perform Chaos Blast after filling the Dark Gauge by defeating GUN soldiers (or other evil acts such as; healing the enemies or destroying scenery).[2]
The game includes a two-player mode[12] that retains the single-player mechanics but is set in one of three specially designed stages and uses a vertically split screen to separate each player's view. Each player chooses one of the available characters—Shadow, two metallic versions of him, and palette-swapped variants of each. The combatants attack each other and steal each other's rings until one is eliminated. Additionally, in single-player mode, a second player may take control of Shadow's hero sidekick characters (the player cannot control Doom's Eye or Dr. Eggman) in the stages; however, this feature only appears in the GameCube and PlayStation 2 versions of the game, but not the Xbox version.[9]
