M.U.G.E.N

M.U.G.E.N is a 2D fighting game engine designed by Elecbyte and originally released in 1999. Elecbyte distributed beta versions that ran under DOS, Linux, and Windows. The engine allows for anyone to create characters, stages and other game objects through interpreted text files and graphics and sound compilations and it also supports various types of audio formats such as MP3, ADX, OGG and MIDI as background music during gameplay. The engine is very difficult to program for unless you're directly copying characters off of others. The engine is powerful and flexible, allowing for the type of functionality found in most any commercial 2D fighting game, such as the Street Fighter games produced by Capcom or the King of Fighters games produced by SNK.

History
From 1999 to 2001, there were several incremental releases of the M.U.G.E.N engine for DOS. Development of the DOS version was ceased when Elecbyte switched to the Linux platform in late 2001. For a time, Elecbyte had posted a request for donations on their site to legally obtain a Windows compiler to make a Windows version of M.U.G.E.N. A number of donations to the Elecbyte site soon followed, as many users would much rather have a Windows version instead--there were problems with using the DOS version of M.U.G.E.N on Windows XP. The new Linux releases added features that the DOS version did not have. There were then promises of a Windows port of the engine, but the development group decided to discontinue the project in 2003, presumably due to leaks made public of a private Win M.U.G.E.N beta that was provided to donators. The Win M.U.G.E.N beta contained a two-character roster limit, locked game modes, and nag screens. A "no limit" hack that removes these limitations was made available in 2004. This Windows version is functionally the same as the last Linux release and is the most widely used version of M.U.G.E.N today. Despite some controversies - modifications made on the actual engine are sometimes seen as an analogue to those made on the creations developed for it, and this is a recurrent topic of discussion among M.U.G.E.N fans (see Fork (software development)). Since development of the engine was halted and no source code has been made available by Elecbyte, there are now some projects in the works to make a clone of the engine from scratch. Some of them present online capabilities, a much sought-after feature. Today, many examples of M.U.G.E.N can be found in combo videos on the video hosting site YouTube.

Legality
The previous license agreements for usage of M.U.G.E.N from Elecbyte have expired and it appears that a new license agreement will never be granted. Thus, any current distribution of M.U.G.E.N has not been authorized by Elecbyte and is technically illegal, although Elecbyte has never taken any legal action; the company has simply disappeared without explanation. Many people chose to continue using M.U.G.E.N despite the lack of a new license. Creations such as characters and stages for use with M.U.G.E.N are not a part of Elecbyte's license, but only the software itself is. So, it is up to the individual whether or not to violate Elecbyte's license by using M.U.G.E.N Elecbyte itself has not made a public statement since 2003, when they stated that the project had "hit a snag".

Most characters and stages are of dubious legality as well, as most are made using sprites and sounds ripped from copyrighted games. For this reason, some standing communities enforced a loose "time-release" rule, whereby they do not allow linking to characters made from recent games. While this has no actual impact on the legality of the materials in question, it has presumably served to avoid any legal pressure from the copyright holders. But some copyright holders, such as Capcom are said to understand that it is just fanart work and don't care about it.

The work material has two categories: the content of the SFF (sprite format, based on PCX images) and SND (audio format based on WAV) files are copyrighted by the respective owners (like Capcom, SNK, etc); the other files, like CMD (command file), AIR (animation file) and CNS (constant and state definitions, the main file of a M.U.G.E.N character) are copyrighted by the author of the character or the stage. Elecbyte stated that the reason why the code files were text-based and directly processed by the engine in this manner was so that users could learn from each other, yet there has been a great deal of controversy regarding permission (or lack thereof) between coders.

Game projects
These are some full game projects made or being made using M.U.G.E.N:
 * Brutal - Paws of Fury Remix
 * DC vs Marvel M.U.G.E.N. Edition
 * Project 2099 - The Fall of The Hammer (A project on the Marvel 2099 universe)
 * The King of Fighters Zillion (In Chinese) (Also called KoFZ)
 * KOFRemix
 * Mortal Kombat M.U.G.E.N. (in Spanish)
 * Super Street Fighter 2 Turbo (In Chinese)
 * Marvel vs Capcom 3
 * Ultimate M.U.G.E.N. Master Battle : Creator Melee
 * Hokuto No Ken - The Fighting Game (in Italian) (a Fist of the North Star fighting game)
 * Babel Sword (In Japanese)
 * Ninja Warriors : Genesis A full original game using motion capture, incomplete