Developed by Western Technologies Inc. and published in 1993 by Sega exclusively for the Mega Drive/Genesis console, X-Men quickly became a critically-acclaimed game. The side-scrolling video game's success prompted a platform sequel in 1995: X-Men 2: Clone Wars. Critics praised both games for their original soundtracks, graphics, and smooth controls, although the first X-Men game is more often cited for its extreme difficulty, even for experienced gamers. Based on the Marvel Comics team of mutant superheroes and its corresponding television show, single or dual players may act as any of the predetermined playable X-Men. Players utilize the X-Men's special talents and weapons while maintaining their health, and can call upon other X-Men for help throughout the game. For example, while playing as Nightcrawler, players possess the ability to teleport to teleport, while as Wolverine they may use their retractable claws and healing powers. Players move progressively through the levels and engage in boss battles with famous X-Men villains, such as Magneto and Apocalypse. In the first game, a virus has infected an X-Men training area, and the X-Men must cope with whatever dangers the room exposes them to until the virus is deleted. The virus is the work of Magneto, who must be defeated in the final level. Developed by Headgames and published by Sega, Clone Wars featured several new playable characters, such as Beast and Psylocke, and a storyline centered on an alien race determined to take over the world. The aliens have been experimenting on and cloning mutants, so the X-Men must temporarily unite with their foe Magneto in order to save humanity and their fellow mutants.