Developed by the American company Elecbyte using C and the Allegro library, M.U.G.E.N. (often stylized as MUGEN, meaning "infinite" or "limitless" in Japanese) is a freeware 2D fighting game engine. Unlike a traditional standalone game, MUGEN is a toolkit and a platform that allows anyone to design, create, and customize their own fighting game. Its core appeal lies in its unparalleled flexibility.

Stock cast pistons have a critical flaw: at RPMs above 6,000, they begin to distort (rock) in the bore. The forged Mugen piston, thanks to its tighter cold clearances and superior rigidity, allows the engine to safely rev to (with supporting valvetrain modifications).

: If a character runs indefinitely in one direction, check your device mapping type. Switch the profile config from analog emulation to a strict digital layout ( auto toggle on standard systems) to clean up centering issues.