Super Street Fighter II Turbo

Super Street Fighter II Turbo (known in Japan as Super Street Fighter II X — Grand Master Challenge), was released in 1994 and featured enhanced speed and difficulty, as well as the first appearance of Akuma. Super Turbo also introduced to the series "Super Combo" techniques.

Super Combos
A Super Combo is a type of special move, usually a more powerful version of a character's special move, that can be performed only under a certain condition and will strike an opponent multiple times. Each player has a Super Combo gauge at the bottom of the screen which is filled up while the character performs their basic and special techniques against the opponent. When the Super Combo gauge is filled completely, then the gauge will be replaced with the word "SUPER". The player will then be able to perform their Super Combo technique by inputting the specific command, which will then reset the Super Combo gauge back to zero. If an opponent is defeated with a Super Combo, then the background will flash red and yellow.

Air Combos
Super Turbo also introduced the ability to perform a combo against an opponent who is in mid-air. Whereas previous versions of Street Fighter II feature a few techniques which would strike an opponent multiple times, Super Turbo was the first game in the series to feature an extensive Air Combo features. Certain basic moves allows the player to strike an opponent more than once in the air and "juggle" them. These "juggling" moves can be connected into a juggling move or a Super Combo.

Extra characters
Super Street Fighter II Turbo allows players to play as versions of characters from the original Super Street Fighter II (officially dubbed "Super characters") in addition to their regular counterparts in the game by inputting a code for each character. The character would play as they would in Super Street Fighter II, with subtle differences. For example, Super Sagat in Super Turbo can now cancel his short kick into any special move, whereas in Super Street Fighter II he couldn't.

This method has its strengths and weaknesses. "Super" characters cannot perform the Super Combo moves and they cannot fall safely from a throw. On the other hand, some features are beneficial, such as at the start of a Dragon Punch, "Super" Ken and "Super" Ryu are invulnerable when they perform their Dragon Punch and cannot be hit out of it, while normal Ken and Ryu can be hit out of it at any point.

Introduction of Akuma
Super Street Fighter II Turbo also saw the introduction of the series' first hidden character, Akuma, known as Gouki in Japan. Should the player succeed in defeating all eight preliminary opponents, as well as Balrog, Vega, and Sagat without using any continues and achieve a high score or reach the final match in less than 25 minutes, Akuma will reveal himself. Once the player reaches M. Bison, at the start of the round Akuma will warp in, and dispose of Bison. There is no name on Akuma's life gauge; the portrait is completely black and the background music changes to Akuma's theme music. Akuma can also be selected by the player by inputting a certain code at the player select screen.

Other new features and changes
Super Turbo was the first Street Fighter game, excluding home versions of the previous games, to feature an adjustable speed setting. The speed can be adjusted on the system configuration by the game's operator or, if the speed setting is set to "Free Select", can be chosen by the player at the start of the game. The player has a choice between three speed settings, from the original setting in Super Street Fighter II to one which is slightly faster than Street Fighter II Hyper Fighting.

Additionally, the bonus rounds from previous versions of Street Fighter II were removed entirely from the game.