What is MUGEN? MUGEN is a free, highly customizable 2D fighting game engine created by Elecbyte. Unlike traditional fighting games, MUGEN is not a game itself but a platform for a game. It allows users to add any character, stage, or screen pack they want. Want to see Goku fight Spider-Man? Or Ronald McDonald battle Sailor Moon? In MUGEN, that’s not only possible—it’s the entire point.