Starsky & Hutch Games: M.U.G.E.N.

(Mugen is a word of Japanese origin, meaning dream, fantasy (夢幻), or infinite (無限).)
M.U.G.E.N is a freeware 2D fighting game engine designed by Elecbyte, written in C with the Allegro library.

First released on July 17, 1999, M.U.G.E.N was initially created for MS-DOS. Development of the DOS version ceased when Elecbyte switched to the Linux platform in November 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. However, the development group discontinued the project in 2003 and shut down their site. Later speculation pointed at leaks made public of a private Windows-based M.U.G.E.N beta that was provided to donators.

The engine uses 7 buttons for gameplay along with the directional keys, in order to accommodate six-button fighters, which use three punches, three kicks, and a taunt.[6] However, characters do not necessarily use all seven buttons, nor need to follow a traditional six- or four-button format. At most, two human players can control characters, with others controlled by the engine's AI; including a demo mode where the computer controls all characters. In addition, several gameplay modes are available via the main menu.

The main mode of play is Arcade mode, where a character fights random characters as in other fighter games. There are also three different kinds of team modes: Single, Simul, and Turns. A fourth mode, Tag, is listed in the EXE along with two related script controllers, but was never used. In team mode, either side can use any of the team modes. Single is identical to not having a team, Simul gives that side a computer-controlled partner who fights simultaneously, and Turns uses a different character for each round of play, varying from a set number usually from 2 to 4 different characters in a row. If set, the characters' starting life will be adjusted according the number of players on each side. If one side has two characters and the other has only one in one of the Team modes, the side with two characters will each have half their respective normal maximum life values. Pre-WinM.U.G.E.N versions of the engine could have this feature adjusted or disabled via the options screen or the config file, but due to the nature of the hack, the option has not yet been reactivated.

Team Co-op is similar to Simul, except both human players fight on the same side at the same time.

In Survival mode, there is an endless stream of opponents, fighting them either one by one or two in a simul match. The objective is to beat as many opponents as possible, with the game ending when the player's team is defeated. The player can choose to play alone or in Simul or Turns mode, though single player mode gives the highest life and life recovered at the end of each round won. Survival mode was last addition done to the engine. As such, it is not present in any of the DOS versions of M.U.G.E.N.

See also:

RandomSelect (http://randomselect.piiym-net.com/) - hosts several versions of M.U.G.E.N., including the high-res versions.
Mugen-Infantry (http://www.mugen-infantry.net/) - has a character database and downloads.
M.U.G.E.N Fighters Guild Network (http://www.mugenguild.com/) - is one of the largest English forums.
Infinity Mugen Team (http://infinitymugenteam.com/) - contains a database and a news section. (English)/(Spanish)/(Portuguese)
Pão de Mugen (http://www.paodemugen.com.br/) — Brazilian site. (Portuguese)/(English)
MugenBR (http://www.mgbr.net/) — Brazilian site. (Portuguese)/(English)
Mugen.pl (http://www.mugen.pl/) —Contains tutorials and M.U.G.E.N creations database. (Polish)/(English)
Wikipedia (http://en.wikipedia.org/wiki/MUGEN) - contains a lot of information relative to M.U.G.E.N.