Special move canceling
Special move canceling (officially called attack canceling) is a gameplay mechanic in Super Smash Bros. 4 and Super Smash Bros. Ultimate. It is exclusive to Ryu, Ken, and Terry. Certain moves can be interrupted with a special move, prematurely canceling the animation of the move.
While there are several ways to cancel an attack animation in the Smash series, including getting hit and touching the ground, as well as the universal interruptibility mechanic, it wasn't possible to cancel an attack during its active frames with another attack prior to Smash 4, as the games were simply created without said mechanic in mind. This changed with Ryu being introduced as downloadable content, where he was given move canceling to make his playstyle similar to that of his home series. This extended to Ken and later Terry in Ultimate, who are also from games that use this mechanic.
The mechanic itself is very simple to execute: the player can activate a move that can be canceled, making sure an opponent gets hit by it, then activate a special move as quickly as possible. If done correctly, the ending lag will be interrupted by the special move. A visual indicator of a successful cancel is the character suddenly changing to the new attack animation in a somewhat jarring way. This is useful for extending combos, as most cancelable moves have relatively little knockback, meaning the player can start with a series of these attacks, then cancel into the special move before the opponent exits hitstun.
List of moves
Special move canceling can be traced to the 1991 arcade fighting game Street Fighter II: The World Warrior. After receiving complaints that the input window for all attacks, but especially special moves in the first Street Fighter game was too strict, Capcom decided to make the input window much more lenient at the expense of a roster-wide nerf to damage. This made inputs much easier to perform, but caused an unintended side effect where players could cancel moves into each other before the opponent could exit hitstun. This is due to the input window overlapping with the attack animation and the game prioritizing the next attack over cooldown. This oversight is often recognized as creating the first instance of modern combos in fighting games, as previously stated, this was not an intentional decision.
The glitch was well received by fans and became an integral part of competitive play. The fast-paced, technical, combo-centric gameplay is what set the game apart in arcades, which encouraged other companies to intentionally include the mechanic. Later Street Fighter games introduced a combo counter that will tally how long a combo lasts to add to a player's high score, which other games also adopted. Some games like Killer Instinct even made a gimmick out of combos, encouraging players to make as long a combo as possible, up into the hundreds.