Hadoken

Hadoken, sometimes spelled Hadouken, is 's neutral special move in Super Smash Flash 2.

Overview
When used, Ryu releases a light blue ki fireball from his hands via a double palm thrust whilst uttering "HADOKEN!". This fireball travels at a relatively medium pace and deals little damage and knockback, making it useful as a "get-off-me" option or as a setup into other moves. Travel speed is dependent on how fast the player presses the special button. However, all variants have low priority, though their knockback is low enough to jab reset.

Input Hadoken
Inputting the original arcade input for the move (down, down-forward, forward, special) makes Ryu perform Input Hadoken, a slightly stronger, albeit not faster Hadoken, with him voicing out the attack with a fiercer voice. The projectile is dark blue in color, and travels the same speed as a held normal Hadoken.

Shakunetsu Hadoken
Performing a semicircle motion towards the direction Ryu is facing (back, down-back, down, down-forward, forward, special) will make Ryu perform the Shakunetsu Hadoken. This version of the move has Ryu launch a orange, flaming Hadoken while Ryu utters "SHAKUNETSU!". The projectile itself, is much faster than the normal variant and deals multiple hits of flame damage, with a stronger launching hit at the end.

Origin
Hadoken, colloquially called a "fireball", is a special move available to several characters such as Ryu and Ken in the  series. It involves the user thrusting their palms forward to fire a blue surge of spirit energy, or Ki. It is performed by the player moving the joystick or D-pad a quarter circle forward towards the opponent from the down position, then pressing a punch button, with the projectile's speed and distance varying depending on the specific button pressed. The creator of Street Fighter, Takashi Nishiyama, credits the 1970s anime Space Battleship Yamato as the inspiration of Hadoken, based off of a weapon called Hadōhō .

The Shakunetsu Hadoken was formally introduced in  as a new move for Ryu, a special red fireball that could burn the opponent. In the original Street Fighter II the regular Hadoken occasionally turns red due to an Easter egg (originally thought to be a glitch), which lead to rumors that this "red Hadoken" was stronger; Capcom thus decided to make the "red Hadoken" a separate move with actual differences in properties (such as knocking down up-close in the Street Fighter Alpha / Zero games). In the Street Fighter III (excluding Street Fighter III: New Generation) and Street Fighter IV games, Shakunetsu Hadoken serves as Ryu's EX version of the move; Akuma being one practitioner of this attack still keeps it as a separate normal special move to this day, as he performs his signature focus stance as a delay before unleashing the move (Akuma's also has always done multiple hits prior to the EX move version).

Trivia

 * In the original Super Smash Flash, fires a Hadoken as his down attack. However, this attack derives from a weapon in  based on the attack of the same name in the Street Fighter series, as opposed to being based directly on the original attack.