A string is a canned sequence of attacks. It is not necessarily a combo, but it can be one.
In the in-game movelist, a single string is usually considered one “move”. Another way to think of it is that the first attack in a string is the “move” and every extra attack is an extension of that move. In either case, each step in a string must be considered, because the attacking player has the option to finish it, but doesn't necessarily need to.
Strings are a large part of the movelists in Tekken. Most of them have some weakness which can be exploited when known, and without knowledge of these weaknesses they can be unreasonably strong, so knowing your opponent's strings and how to deal with them is a significant part of matchup knowledge. Nonetheless, many strings even once known are real threats, either because of a favorable risk to reward, mental frame advantage, or simply the difficulty of punishing them accurately.
In addition to the usual attack properties, in a string—
- A delayable move gives the attacking player the option of doing the move later than usual by delaying its input.
- A jailing attack forces the defending player to guard if the previous attack was blocked.
- A natural combo (or neutral hit combo) is an attack that can't be blocked after a previous attack in the string hits.
- In some cases, the attack is only guaranteed when the previous attack gets a counter hit.
For non-delayable moves, the latest the input can be done is the last active frame of the previous move.
For delayable moves, the input can be done later than this. However, the input being delayed does not always delay the move itself—some moves have a natural delay, and delaying the input simply matches this. Many moves have a very small natural delay (1 to 3 frames), and it's common for moves to both have a natural delay and be delayable beyond that.
The longer an attack can be delayed and still be a natural combo, the easier it is to hit confirm.
When an attack in a string is blocked, the next attack can often be beaten by one of:
- Sidestepping, if the attack is linear
- Blocking, if the attack is punishable
- Ducking, if the attack is high
- Low parrying, if the attack is low
- Interrupting it, if the attack is slow
As a general rule, every extra mid and extra option in a string makes it more likely to have a fatal weakness. When a string jails, this is generally treated from a balance perspective as though the two attacks are a single one, since a defender can safely attack into it without being counter hit.
Mental frame advantage
Mental frame advantage refers to the situation where a defender trying to react to an extension not being done before taking their turn effectively gives the move better frame advantage. This is influenced by:
- How long the blockstun is
- How delayable the extension is
- How fast the defender can react, which is influenced by—
- The defender's raw reaction time and input delay
- The defender's familiarity with the string
- How visually distinct the extension's animation is
- The extension having an audio cue
For example, Yoshimitsu's d/f+1 is -4 on block. If the defender takes their turn to attack and Yoshimitsu does d/f+1,2, he gets a full combo. A more cautious defender could try and react to the extension not being done before attacking. However, the blockstun is only 19 frames, and the animation for d/f+1,2 doesn't appear to begin until the the 7th, giving the defender 13 frames to react. Against a defender who takes, say, 20 frames to react, the mental frame advantage effectively causes d/f+1 to go from -4 to +3 on block.
This concept is distinct from the defender not reacting and either taking the risk of attacking into the extension or using an option select.