X-Men: Mutant Academy on the Game Boy Color is a fighting game. Due to obvious limitations on hardware, the stages in this version have been rendered in 2D, and the gameplay is different from the PlayStation version. In addition to Story Mode, where one player takes on all the others in consecutive fights, there is training mode, battle mode, survival mode, and a versus mode utilizing the Game Link cable. During a fight, a rage bar will slowly fill, which allows using powerful special moves that are activated through button combos.
Source: Wikipedia, "X-Men: Mutant Academy", available under the CC-BY-SA License.