TKI is a very popular opener among Tetris players where you send a TSD from the very start with your first bag. Originally devised by player TKI.
This opener is very fast to execute as it only needs 5 to 6 pieces from the first bag to complete the first T-Spin Double, and the only requirement of this opener is an early I. Another advantage of TKI is that it leaves a low and clean field after the first TSD, making it easy to follow up with subsequent TSDs or downstacking.
Note: TKI refers to C-Spin in the Japanese community
The opener itself is very simple. You make this basic shape and do a TSD.
You can just harddrop I and Z without any rotations or movements from their spawn positions.
TKI can be harder for beginners to use because there isn't exactly a set followup that you use after you do the initial TSD, which means that you will have to improvise in many cases. Although many followups to TKI are done freestyle, there are certain variations and certain followups that are used by players when the upcoming pieces allow you to do that specific followup.
Here's an example: Bag 1 is ZIOLTSJ, Bag 2 is JTIOLSZ, and Bag 3 is SILTJOZ. The player chooses to use TKI with his first bag and decides to do the flat top variation. Most players prefer to do LST Stacking when they use the flat top variation, and here, the players second and third bag allows the player to continue with LST Stacking and therefore he chooses to do so.
Here's another example: Bag 1 is SLIOTJZ, Bag 2 is LSJZITO, and Bag 3 is OTJZLIS. The player chooses to use TKI with his first bag and decides to do the fonzie variation. Stacking the second bag in a way that gives the player a chance to PC is preferred, and the second bag allows the player to do this. The player luckily gets an early O on the third bag and does a perfect clear.
Last example: Bag 1 is TSIZOLJ, Bag 2 is ITZOLJS, and Bag 3 is STZOLIJ. The player chooses to use TKI with his first bag and decides to do the fonzie variation. Although it would have been nice to stack in a way that gives the player a chance to PC, the second bag doesn't allow the player to do so. Therefore the player improvises on his second and third bag.
The last example is representative of many cases where you will have to improvise on your second bag and onwards, but as shown on the first two examples, given the right pieces, there are certain followups that you can follow. The rest of this page shows widely used followups to TKI, including the ones shown on the first two examples.
examples on this section are from kazu's plays
Most variations are divided by where you put your J(L). The pictures below show the fonzie, flat top, castle top, and snail variation, respectively.
Below are other variations that are less commonly used depending on the player's preference.
The third variation above is unique in a sense because it's a variation that you can use even when you have a somewhat late I. Here are some example first bags for when you would use this variation: LZSOITJ, LTZIOSJ, OSJLITZ, IOLTZJS
The fonzie variation is usually possible when you have late J.
People usually try to make these shapes when continuing with this variation because it gives you a chance to do a perfect clear. Here are some other ways to get a perfect clear.
If a perfect clear is not possible, players often make a STSD,
or recognize that a perfect clear is not possible early and stack differently, like:
Another way to continue is to create a field like below with ILS (first picture) or SZL (second picture).
The resulting field after doing the TSD is compatible with transitioning into LST.
Here are a couple of examples on how you would do that.
For this variation, Z must come before J. 99 out of a 100 opponents will attempt to continue with LST Stacking if they open with this variation.
Below are some ways to build 2nd TSD.
If you have late O, you can use donation techniques like below.
After the 2nd TSD, many people will continue with LST Stacking which is a very practical stacking method.0
You can also make Imperial Cross from flat top continuation. You will need an early J then an early Z.
The first picture above is the preferred way to build it because you'll have an opportunity to do a perfect clear. Here is an example (screen on right).
The first image below is the easiest solution to recognize and memorize. The second image below has the second most commonly used solutions where you do a TSS. With these solutions, you have a 80.54% chance of PC. The other remaining solutions can be seen here. The total chance will go up to 89.68% with those.
This Double TST followup is used when LST Stacking is not feasible based on your queue, which is common when the third bag starts with ZJ.
This followup is also used when LST Stacking is not feasible based on your queue, most commonly when you're given a third bag starting with ZJ. You briefly do ST Stacking before doing a donation like the last picture below. The overhang for that TSD is variable.
There is a PC opportunity if you build the second T-Spin this way.
The chance itself is 42.38%, but if you get an early S and if you can place it like below, you will have a 77.78% (560/720) chance to do a perfect clear with just 3 solutions.
This is an uncommon variation that is most notably used by player kazu. Just like the flat top continuation, people will attempt to continue with LST Stacking if they open with this variation.
This variation is harder to continue with LST Stacking compared to the flat top variation, but its advantage is that you can avoid doing any softdrops for certain queues (e.g., JZLISOT) that would require a softdrop if you continued with the flat top variation instead:
The second TSD is mainly built in two different ways, depending on whether you able to place the Z on top of the L or not. If you get an early L, you are guaranteed to be able to continue onto LST.
If you are unable to do this, your stack becomes more complicated because you will need to do a donation involving O. The middle picture below is preferred.
These are some other ways to follow:
You will have a 100% chance of doing a perfect clear if you have either an early Z or an early O that you can place like below.
These are the solutions that you'll need if you were able to place a Z:
The only requirement for castle top is O coming before J.
People usually try to make this shape because it gives you a chance to do a perfect clear with a L or an O in your 3rd bag.
If you have early T, you could stack like below which gives you a 100% chance of doing a perfect clear. Solutions can be found here.
If you have an early Z, you can follow up with Imperial Cross. If you can build it like the 3rd picture shown below, you will have a high chance to get a perfect clear (89%). The solutions are same as the Imperial Cross PC done with the flat top variation, shown above.
thanks to popte for the tip on LST continuation for Fonzie