M.U.G.E.N
MUGEN is a 2D fighting game engine developed by Elecbyte. The content is created by the community. Thousands of fighters, both original and from popular novels, have already been created.
Story
Authors often port popular characters from 2D fighting machines like the Street Fighter series, or from television, book, and game series like Teenage Mutant Ninja Turtles, The Simpsons, Pingu, Super Mario, Sonic The Hedgehog, Pokémon, Sailor Moon, and Touhou. Many creators also create their own content. There are many websites where the developed content and forms are presented and distributed in the so-called "Mugen community". Games developed with the M.U.G.E.N. engine often focus on a specific franchise, such as Hyper Dragon Ball Z. Since the game engine is customizable, no two versions of M.U.G.E.N are alike. Everyone can download their own version of the game engine and create or add contents according to their personal preferences. Groups of M.U.G.E.N authors often work together to create a complete game using the engine. These complete games are available in various quality levels and are released under the general M.U.G.E.N. license. "Under this license, permission is granted to use the M.U.G.E.N environment free of charge for non-commercial purposes.... Elecbyte provides a redistributable M.U.G.E.N package that contains a minimal M.U.G.E.N environment that can be redistributed with third-party content.