Super Street Fighter II Turbo (known in Japan as Super Street Fighter II X: Grand Master Challenge) is a 2D fighting game developed by Capcom and released for the arcades on February 23, 1994. The fifth official iteration of Street Fighter II builds upon Super Street Fighter II: The New Challengers by adding new moves (such as the Super Combo, a special powerful technique for all characters that can only be activated after building up the new Super Meter) and an adjustable speed setting (which must be turned on by the operator), allowing players to ramp up the speed up to a level similar to Street Fighter II': Hyper Fighting. This also marks the first in the series to remove the bonus mini-games that occurs between every few consecutive matches.
Each fighter, along with new moves, also have a variety of changes to their gameplay mechanics (for example, Ken has a wide variety of new kicks) and a new primary color palette (in similar vein to Street Fighter II': Hyper Fighting). Players can, however, play as the Super Street Fighter II: The New Challengers version of each character (removing the Super Meter, reverting most character changes, and giving the original color palette back) by inputting a special cheat code. The game also includes a new hidden boss, Akuma (known in the Japanese version as Gouki), who is shown in promotional artwork and the game's introduction sequence. Believed to be born out of the Sheng Long hoax, this fighter has a variety of powerful moves (including the ability to throw fireballs in the air) and can only be fought by progressing through the difficult single-player game without continuing under a certain condition (either achieving the high score before reaching M. Bison, or reaching M. Bison in under 25 minutes).
Between 1994 and 1996, the game has been ported to the 3DO (published by Panasonic for the U.S. and European regions and published by Capcom for Japan), MS-DOS (ported by Eurocom and published by Gametek), and Amiga (including Amiga CD32, ported by Human Soft and also published by Gametek). Unlike the previous iterations of Street Fighter II, the ports authentically replicate the graphics of the arcade version. The MS-DOS and 3DO versions have remixed music (with the 3DO music having the same remixed music as the FM Towns version of Super Street Fighter II: The New Challengers). The game was also ported to the PlayStation and Saturn on November 30, 1997 as part of the Street Fighter Collection compilation and ported to the PlayStation 2 and Xbox on November 14, 2006 as part of the Capcom Classics Collection: Volume 2. The game was also ported to the Dreamcast in Japan as an exclusive mail-order release on December 22, 2000, titled Super Street Fighter II X for Matching Service. This port includes an online versus mode, the return of bonus mini-games, and hidden secrets (including two alternate versions of Akuma: Shin Gouki and Tien Gouki).
Super Street Fighter II Turbo is the last official iteration for nearly ten years, proceeded by Hyper Street Fighter II: The Anniversary Edition and later by Super Street Fighter II Turbo HD Remix.