Despite being an acronym, it is not known what M.U.G.E.N stands for as even Elecbyte have since forgotten, though its name is supposedly derived from its time as a shooting game. Elecbyte have said that some of the inspiration for M.U.G.E.N came from games such as SFIBM, an unlicensed PC port of Street Fighter II. M.U.G.E.N started off as a PC shooting game, though Elecbyte made the change from a shooter to a fighting game when they noticed 'there weren't any good commercial fighting games on the PC at the time'. M.U.G.E.N has a fairly large community, with multiple forums and sites dedicated to the engine, as well as many internet videos with the purpose of teaching users how to use and customise the engine or (more commonly) broadcasting M.U.G.E.N fights.

Being a fighting game engine at heart, M.U.G.E.N takes inspiration from a variety of classic fighting game series such as Street Fighter and The King of Fighters, featuring a seven-button combat system ( Ⓐ, Ⓑ, Ⓒ, Ⓧ, Ⓨ, Ⓩ, and Ⓢ ), typically representing three punches, three kicks, and a taunt, though characters are not limited to having those presets, with many opting to use fewer buttons and less traditional button layouts. M.U.G.E.N allows users (typically known as 'authors' or 'creators') to create content for the engine such as (but not limited to) characters and stages for others to download and add to their game, or just to keep for themselves, as well as fully-fledged fighting games. The most recent version of M.U.G.E.N to be publicly released is version 1.1 Beta 1, which was released on August 7th 2013, though the most recent stable build is version 1.0, released on January 18th 2011. M.U.G.E.N (also written as MUGEN and Mugen officially pronounced 'moo- gen' ) is a freeware 2D fighting game engine developed by Elecbyte. The default motif for versions 1.0 and 1.1 of the M.U.G.E.N engine For the article about the character based on the engine, see M.U.G.E.N (character).

This article is about the M.U.G.E.N engine.

Mugen 1.1 sonic stages