Akuma (known as Gouki in Japan) is Gouken's brother, and a student of Goutetsu, as the two were taught by the same master. Gouken left Goutetsu´s dojo after knowing he was teaching an evil art, or the Satsui No Hadou. Akuma, however, pursued the path of the Satsui no Hadou, becoming an almost demonic figure. After killing his master Goutetsu in battle, Akuma seeks to completely master the Satsui no Hadou, and for such he searches for strong opponent to which he can have a fight to the death. He eventually learned that Ryu has a latent Satsui no Hadou ability, so he tries to make Ryu follow it's path, though Ryu, knowing it is an evil power, struggles to get rid of it.
Akuma has a twisted moral code, as he himself does not challenge anyone and refuses to fight with anyone he perceives as being weak, since all of his fights are intended to be fights to the death. He also avoids using his full potential to avoid ending fights prematurly.
In M.U.G.E.N, Akuma has been made by various creators.
This Akuma character has custom gameplay, with 5 Modes: Akuma, Normal Akuma, Shin Akuma, Oni, and Master Akuma, 120 Win Quotes, brutal AI, pretty much every last Classic Akuma move ever seen in video games, winane A.I. method and special animations. However, it only works for M.U.G.E.N 1.0.
GM's Gouki (Third Strike)Edit
This Akuma is closely accurate to the original game. It also has a Shin mode accessed by pressing the start button and any attack buttons. He has two secret super arts, only useable with a full super meter: Raging Demon and Kongou Kokuretsu Zan. Like others GM's Street Fighter characters, you can select one of his Super Arts, or use then at the same time (Except Shun Goku Satsu and Kongou Kokuretsu Zan). It's available for WINMugen and MUGEN 1.0.
Vyn's Gouki (SMvC)Edit
Vyn's version has MvC2 effects but the hitsparks and voice are from CvS. The gameplay is custom-made, and this version of Akuma can do air combos.
There's also a SFA/MVC2 voicepack by MultiJosueh for this Akuma.
Master Gouken's Gouki (SFA3 + CVS2)Edit
Master Gouken's Version has SFA3 effects but with the CvS2's transparency. The gameplay is custom-made, and this version of Akuma has the SFA3 and Cvs2's Voice and Sound Effects.
felineki's Akuma Edit
felineki's Akuma plays like its Super Street Fighter II Turbo counterpart, and does so literally. Not only does he maintain his moves from Super Street Fighter II Turbo, he is also known to dizzy opponents. Besides the Normal and Shin modes, he also has a Ten mode, which allows him to use the Super Combo, similar to the Dreamcast version of Super Street Fighter II Turbo. This Akuma was later updated with some improvements.