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, Street Fighter Alpha 2||+ / while blocking|
|Street Fighter Alpha 3||+ ( + of the same strength) while blocking|
|Capcom vs. SNK 2 (C-, A-, S-, and N-Grooves)||+ while 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 (in Street Fighter Alpha and Street Fighter Alpha 2), or holding forward and pressing any punch and kick buttons of the same strength (in Street Fighter Alpha 3), 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 Alpha, each character would use either the punch or kick button, depending on the character in question. In Alpha 2, all characters use both buttons, with one corresponding to high attacks, and the other to low. In Alpha 3, characters once more have only one Alpha Counter, as two buttons must be pressed at once to execute it.
Also, in Street Fighter Alpha 2, one has to keep an eye on the Super Combo Gauge to determine if they have enough meter built to do an Alpha Counter; In Street Fighter Alpha 3, this affects the Guard Power Gauge instead, and may result in situations where the character can easily be guard crushed if Alpha Counters are used haphazardly.
Not all Alpha Counters will outright knockdown an enemy, especially in Rose's case, where her punch Alpha Counter will perform an exclusive move, called Soul Passing.
The function returns in Capcom vs. SNK 2 (in which it is simply called "Counter Attack") as a function of the C-, A, S-, and N-Grooves. In this game, the player must press both medium attack buttons (no additional directional input is needed) while blocking. Unlike in the Alpha series, this affects neither the Super Combo Gauge nor the Guard Power Gauge and can be used freely.