The Grim Adventures of Billy & Mandy is a 3D arena-based
fighting game, similar to other games in the same style such as
Power Stone. In the game, up to four players battle in a three dimensional arena and perform light and heavy style attacks in an attempt to deplete their opponents' health and knock them out. Only Billy, Mandy, Grim, and Irwin are initially available; all other characters must be unlocked through gameplay.
Game Boy Advance version The
Game Boy Advance version follows the same plot as the console version, but is instead a sidescrolling
beat 'em up with
platforming elements. Players control Billy, Mandy, and Grim as they traverse 2D stages, fight enemies, and jump over obstacles. Enemies will appear at predetermined points in stages and attack the player, all of which must be defeated to continue progressing through the stage. Defeating enemies will increase the player's Mojo Meter; when filled, the player can enter a temporary powered-up state, in which their character will be rendered invincible and able to instantly defeat any enemy they touch. Like the console version, weapons will sometimes appear which can be used to more easily defeat enemies. The main Story Mode features a brief campaign for each character, each consisting of a handful of short stages before concluding with a boss fight: Billy battles General Skarr in Endsville, Mandy pursues Jack in the pumpkin patch, and Grim confronts Nergal in the Underworld. Only Billy's story is initially available, while Mandy and Grim must be unlocked; players must complete all three stories to see the game's ending. A mission mode is also available with several unique scenarios for players to complete. Each time the player completes a story or mission for the first time, they will earn a Mojo Ball, which are used to unlock the other story campaigns and missions. Collecting all 54 Mojo Balls unlocks a concept art gallery. ==Plot==