Mugen is a 2D fighting engine for PC platform that was made by accident when trying to develop a game they where working on. Basically it is a 1 on 1 or 2 on 2 fighting platform to the likes of Street Fighter and Mortal Kombat style games. All you need to do is download and install, then find the characters you wish to play as and install them into the game and you can instantly have Street Fighter Chars VS Mortal Kombat chars as well as just about anything else you can think of in the video game fighting world… even some that had nothing to do with fighting
MUGEN FIGHTING JAM (WinMUGEN set up with 500 char. slots):
http://www.megaupload.com/?d=VOPC5A3V
MUGEN (command prompt mugen):
http://www.mediafire.com/?7pmd0zen0uh
WinMUGEN (Recommended for XP Users):
http://www.mediafire.com/?c12ejqbfj1g
Enjoy! 
MUGEN GAMES:
#1:
King of Fighters vs. Street Fighter Zero 3
http://rapidshare.com/files/49524761/KOFvs.SFZ3_K29.rar
Pass:Warez-BB.org
Star Wars:
http://rapidshare.com/files/49664326/WinRAR3.70_LPL.zip
Pass:Warez-BB.org