Ryu brings his palms back beside himself to cup them together, then thrusts them forward in an instant to shoot out a large energy projectile while announcing the technique's name. Only one Hadoken per player can be in play at any given time; attempting a second Hadoken if the first one is still active will result in them performing the animation with only a puff of harmless smoke appearing from their hands.
As with most of Ryu's special moves, performing specific direction inputs changes the properties of the Hadoken (this does not apply to Ken's variant). Each version has low speed and variable damage, and travels half of Final Destination's length; because of these properties, all variations of the Hadoken are ineffective at KOing, but good for racking up damage at range, useful in Ryu's tapped tilt combos, and can be used as a option to wall off opponent's approaches, albeit being less effective than other projectiles like Megavitamins due to the limit of one active Hadoken per player. Shooting the projectile midair gives Ryu a tiny amount of lift, like Mario's Cape; this does not occur if Ryu fails to produce a projectile due to another one being in play.
All versions of Hadoken have extremely low priority and can be blocked by almost any attack, including extremely weak projectiles, which makes Hadokens easy to counter at a distance. Additionally, the projectile can miss certain crouching or prone characters due to its traveling height, while a select few can even run directly under one (such as Little Mac).
Ken, who is Ryu's Echo Fighter, shares this move. Aesthetically, his version has a slightly different shape and contains an image of his hands. Compared to Ryu, Ken's Hadoken is weaker, and its speed is less controllable; additionally, he does not have access to the Shakunetsu Hadoken.
Pressing only the special button performs the standard Hadoken, a small blue energy projectile, while Ryu voices out "Hadoken!" in a slightly stern voice. The damage and speed at which the projectile moves can be altered based on how long the button is held. It deals 5-6%, with low enough knockback that it can jab reset opponents.
Inputting the original arcade input for the move (down, down forward, forward, attack/special) makes Ryu perform a stronger Input Hadoken, with him voicing out the attack with a fiercer voice. The projectile becomes slightly larger and minutely stronger in the process, doing 6-7% damage, but still travels slowly with similar range as the original. The attack emits a tiny spark if the player successfully inputs it correctly, similar to the spark seen by fastfalling fighters. Ryu can also perform this while in standby after breaking the Smash Ball.
Performing the move while moving the control stick in a semicircle towards the direction Ryu is facing (back, down back, down, down forward, forward, attack/special) will unleash a Shakunetsu Hadoken (灼熱波動拳, Scorching Heat Surge Fist). Ryu voices out "Shakunetsu!" as this Hadoken is unleashed. This variation is colored bright orange, deals multiple hits and flame damage before exploding upon hitting an opponent. The projectile deals a total of 7-8%; like other versions of the move, however, its knockback is weak and distance unchanged. The first hit doesn't make the opponent flinch, making it possible for them to shield the rest of the attack.
True to the series, Ken is unable to perform this attack, instead using Oosoto Mawashi Geri (大外回し蹴り, Big Outer Roundhouse Kick), a roundhouse kick from Super Street Fighter II Turbo. This move can be cancelled into his Inazuma Kick (稲妻かかと割り, Lightning Flash Heel Splitter), a heel-dropping axe kick on either hit or during the move's startup by holding the attack button.
Both Ryu and Ken can perform a Hadoken out of some normal attacks, a mechanic known in their home series as special-cancelling. By pressing the special button or doing the command input after connecting with a normal attack, Ryu and Ken will cancel the endlag of the normal attack and perform a Hadoken. The normal attacks that can be canceled include the first two hits of neutral attack, tapped and held down-tilt, tapped up-tilt, and proximity forward-tilt and held neutral attack (in Ultimate), to name a few. This allows them to deal extra damage in combos, improving their punish game.
Copy Ability (Kirby)
Kirby can also perform all versions of the Hadoken once he Inhales Ryu or Ken, by inputting the same motion on the control stick. He voices out all attacks like Ryu as well, albeit in his more lighthearted voice; attempting to shoot a Hadoken while one is still in play makes Kirby voice out a short "Hoh!", unlike Ryu, who simply scoffs. Kirby can also perform the inputted and Shakunetsu Hadoken variants while in standby after breaking the Smash Ball. Interestingly, Kirby has different voice clips for Ryu and Ken's versions of Hadoken.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
Like the other DLC characters, Ryu lacks custom move variations.
Hadoken, colloquially called a "fireball," is a special move available to several characters such as Ryu and Ken in the Street Fighter series. It involves the user thrusting their palms forward to fire a blue surge of spirit energy, or Ki. It is most commonly 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 (波動砲, lit. Wave Motion Gun/Surge Cannon).
In the main Street Fighter series, Ryu, as well as other Hadoken practitioners, cannot perform a Hadoken in midair, but they can in some crossover games like Marvel Vs. Capcom, where it is known as the Kuchu Hadoken/Kuuchuu Hadouken (空中波動拳, Midair Surge Fist) in Ryu's case mainly.
The Shakunetsu Hadoken was formally introduced in Super Street Fighter II: The New Challengers 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).
Note that in Super Street Fighter II Turbo Ryu's Shinku Hadoken was also referred to as just the Hadoken, as none of the characters' Super Combos were properly named onscreen in their debut. This was changed in Street Fighter Alpha.
Like with many of Ryu's other moves/techniques, this is the arguably the most codifying example of a projectile attack in any fighting game. While most games would only allow one copy of a projectile to be on-screen at a time, later games allow multiple copies of them to be on-screen. This is played straight for Ryu's Hadoken in Marvel vs. Capcom 3 with the latter case.
In a majority of games, users of this technique will have an image of their palms grafted onto the projectile itself when one looks at the projectile itself closely.
In particular however, the Hadoken's size in Smash Bros. is more likely based off of the Marvel vs. Capcom series' version, where starting with X-Men vs. Street Fighter, several Street Fighter characters' moves were given radical changes in order to look less pale in comparison to the X-Men characters, with the Hadoken's size increase being one radical change out of many.
Though Ken has always used the Hadoken alongside Ryu, his usage of it is far more restricted, often being inferior in various aspects such as being punishable on hit when close to the opponent. He is characterized as being flashier and preferring kicks, leading to his Shoryuken being more powerful than Ryu's and forgoing the Shakunetsu Hadoken for other attacks like his Roundhouse Kicks.