Auto Combos
From UltimateMK.com
Auto Combos refer to the dial-a-combo system that was added to the series with Mortal Kombat 3. However, the autocombo is based very heavily on gameplay elements that existed in MKII and MK.
How They Work
An autocombo is a series of attacks that link together in a very structured way. For instance, Kabal has the autocombo HP, HP, HK, B+HK. If you are near your opponent and tap that sequence quickly you will most likely do all 4 hits of it.
The way an autocombo works is you must be very close to your opponent for the first hit of it to come out. If you are too far away a regular punch or kick will happen.
Once you press an attack button, your character will begin that attack. You can press the next button in the sequence immediately after. When an autocombo hit connects, your character will hold the last frame of tha hit, and you have until he begins to recover from the held frame to press the next button.
However, the number of frames each autocombo hit can have varies while the amount of time your opponent is left unable to respond does not. This means that some you can press the buttons of the combo relatively slowly (you can wait for the current attack to connect) and the combo will not break. Some autocombo hits with more frames of animation must be done much faster. For instance if you are doing Human Smoke's HK, D+LP, D+HP, the D+LP attack has a lot of startup. If you do not press D+LP before the HK connects, there is a chance the combo will break.
Another factor with the above combo is the nuance of stun time on your opponent. Your opponent recovers faster from the first hit of an autocombo than from the other hits. That's in addition to the long startup of the D+LP is why that combo will break if not done quickly.
Origin of Auto Combos
Autocombos are based heavily on pre-existing gameplay elements. In the first 2 Mortal Kombats, pressing an attack button right next to an opponent would cause you to do a unique move for your character (Kano's headbutt or Johnny Cages popup kick for example). The first hit of the autocombo works the same way.
The window to press the next button in the autocombo sequence is the same as how rapid punches work. With rapid punches, after the punch starts, you have until the character begins to recover from the held frame to press for the next punch.
In Mortal Kombat II Baraka had a 2 hit kick that functioned in almost the same way that autocombos eventually functioned. However, the opponent could block the second hit even if the first connected.
The main addition to make autocombos function was to create the chain of moves following the same principals as rapid punches and near hits and add a stun period after each hit to make the combo unblockable.
Autocombos can branch off at different points, similar to alternating between HP and LP during rapid punches. And many autocombos are popup moves just like Johnny Cages popup kick near move.
