Alpha Counter (ゼロカウンター, Zero Kauntaa) is a maneuver first introduced in the Street Fighter Alpha series.
|Street Fighter Alpha series||+ / when blocking|
Alpha Counters are performed by executing a quarter-circle forward motion (specifically a "9-to-6 o' clock" motion) and pressing either kick or punch while blocking; if done properly, the user will block their foe's attack and counter with a predetermined special attack, which will send the opponent spinning to the ground.
In the original Street Fighter Alpha, each character would use either the punch or kick button, depending on the character in question. In Street Fighter Alpha 2 and 3, all characters use both buttons, with one corresponding to high attacks, and the other to low.
Also, in Street Fighter Alpha 2, one has to keep an eye on the super combo meter to determine if they have enough meter build to do an Alpha Counter; In Street Fighter Alpha 3, this affects the Guard Meter instead, and may result in situations where the character can easily be guard crushed if Alpha Counters are used haphazardly.