MUGEN, which stands for "Mortal Kombat Universal Game Engine," is a free, community-driven game that was first released in 2008. Developed by a team led by Akuma's creator, Eelco "Elabee" Hoppen, and later maintained by other dedicated fans, MUGEN allows players to create and play custom Mortal Kombat-style games. The engine supports an incredibly wide range of features, from customized characters and stages to unique gameplay rules and story modes.