Stick Fighter 2 is a very cool stick fighting game.
The special key alters moves. Holding it down in conjunction with the other buttons will make your character perform different moves. e.g. holding special and kick will make your character kick multiple times.
Some buttons on the keyboard can be held along with the special button and ordinary move buttons to perform hidden moves.
Holding down the punch and the kick buttons at the same time will make your character start "Powering Up" (regain health). Letting go of one or both of the punch and kick keys will cause you to stop powering up. This move can also be altered with the special key.