X-Men: Mutant Wars is a side-scrolling beat-'em-up in which you take control of the X-Men (including Wolverine, Storm, Iceman, Gambit, and Cyclops) and must use the powers of each to fight your way through the many levels of evil mutants, crazy machines and boss characters including Magneto.
You can change the character at any time during the game, which is important as your characters power level decreases as you go. When you change a character, the character you take out rests, and the power level increases. Also, some areas can only be completed by using the certain powers of each character.
Apart from the normal mode of play, you can also play a second version, where you must fight all of the Boss characters, and if your character runs out of power, you cannot use him/her again.