Ryūken

Ryū-ken is Super Saiyan Goku's side special move in Super Smash Flash 2. Super Saiyan Goku transforms into Super Saiyan 3 form and releases a dragon shaped projectile from his fists, resembling Shenron. Also, the player cannot attack until after the projectile has left the boundaries, but this was a "bug" that got fixed in the demo v0.8b. In v0.9b, the projectile no longer drags opponents off screen but instead hits opponents multiple times.

Origin
In the anime and manga, the Dragon Fist Ryū-ken also known as Ryū-Ken Bakuhatsu or Chō Ryū-ken  is the only technique Goku comes up with completely by himself. He begins the attack by making a straight fist faced at his enemy, then once his fist, along with his own body, exits the stomach or chest of the target, the energy will explode out into the form of an enormous golden dragon which bears a great resemblance to Shenron and then finally collides into the target, possibly destroying it in its path or leaving a gaping hole, hence the name, Dragon Fist.