C-Spin

The C-Spin (TKI積み) is a kind of Triple Double Attack. It is invented by TKI. This name is given because of the "C" shape that is formed by the J and L. As the name suggests, it results in a T-Spin Triple which is usually followed by a T-Spin Double within three bags. As an opener, it is most often built with an ZST core whereas L and J are used to build the overhang.

It is difficult for beginners to use the C-Spin opener because accidents are likely to happen.

C-Spin Opener
There are many C-Spin openers, both with a vertical T and horizontal T piece. In this page, some of the most notable setups are listed. However, for some openers, stacking the second bag is fixed.


 * ZST Core: This is the most common C-Spin opener. If the S and Z pieces come early in the first bag, this is a good opener to use. The second bag must be stacked freely but if you can place the Z piece early, the whole stack will be stabilized. Below is an example with a Trinity followup in the third bag.



While the L, Z, S and T pieces are in the same places, the placement of the O and I pieces the right side, sometimes along with the J piece (the second bag's J piece can also be used to build the overhang), will vary, but the most common way shown is in the first diagram.



Similar things are also possible in the case of a 2-columns wide gap, and especially for the third diagram shown below, it can either result in a Perfect Clear or T-Spin Triple.



If you keep the first bag's O or I piece on hold, you can use a Donating T-Spin Triple technique. Below are some examples on how you may utilize this technique if you keep the I piece on hold (the final 3 examples keep the first I piece on hold entirely).


 * TOJ Core (TKI signature): In the second bag the S, Z and O pieces always form this "Plus" shape which can be done in 4 different ways. If you are aiming to achieve a Perfect Clear in the third bag, you must place the pieces differently, except for J and T.


 * IST Core: It is best if the first O piece is placed on the far right as this will allow the second bag to be always stacked differently, alongside the traditional way. In the case of the latter, it is continued with a Trinity.


 * ITZ Core: Like the ZST and TZJ Core setups, the second bag is stacked improptu. However, there are quite some ways you can stack the second bag in such a way you can achieve a Perfect Clear after 6 or 8 lines in the third bag.


 * ITO Core: You can always stack the second bag in the way shown in the third diagram or sometimes, the one in the second diagram.


 * TZJ Core: This setup is invented by Aitch. This setup can always be assembled if the I piece comes early, but the TKI 3 Opening is more appropriate if you get an early I. Normally, the J piece would be on hold, but for this example, it is placed on the L piece. You must spontaneously stack in the second bag. For example, the S, Z and O pieces are placed along with a late L piece.


 * ZOT Core: In the first bag, the first J piece can be used as the overhang but it is better to use it in the stack because it will be easier to stack the second bag, even though you still have to stack freely. If you are aiming to achieve a Perfect Clear in the third bag, then the ways to stack the second bag is fixed.


 * TSZ/ZOT Core: There are two ways the first bag can be stacked, shown below. In the second bag, the notch can be made with L and Z, or simply an I piece, while the rest is stacked freely. The final two diagrams shown may give you a chance to achieve a Perfect Clear.

C-Spin Opener Continuations
Aside from simply making a T-Spin Double, there are several options on how any C-Spin opener can be continued in the third bag.

T-Spin Triple and Imperial Cross
No matter how wide the gap between the overhang and the stack on the right is, you can replace the T-Spin Double with a T-Spin Triple or Imperial Cross after the T-Spin Triple from any C-Spin setup.

STMB Cave
The STMB Cave continuation will only work if the following cells in diagram 1 (marked with X's) are free. If one of them is occupied, you can try making a T-Spin Triple or Imperial Cross.

Trinity / STSD
If you used a J piece as the overhang and there is an S piece or nothing on the overhang, you can make a Trinity (if the TSD is not done beforehand) or STSD (if the TSD is done beforehand) by placing an S piece on the overhang.



Fractal
If you have a 4-columns wide gap, you can place the third bag's Z and S pieces as the base, if the second Z piece was placed on the overhang. There a lot of continuations after the Fractal, such as LST Stacking if there is a J piece on the Fractal overhang, or in this example, STMB Cave.

LST Stacking
Generally, if you have a 2-columns wide gap, you can follow with LST Stacking by placing an L piece on the overhang. Furthermore, if the Z piece can be placed after the T-Spin Double, you will be able to score a T-Spin Double at any time. Otherwise, place it in the stack and use the fourth bag's Z to make the base.

T-Spin Triple Tower
If there is a Z piece on a J piece overhang, regardless if that Z piece is from the second or third bag, you can stack a T-Spin Triple Tower after a T-Spin Double. This is usually a fairly risky followup, especially because it requires one to stack the 7 rightmost columns relatively high. Sometimes, one may place the I piece after the T-Spin Double to help with stacking the fourth bag.

Perfect Clear after 6 lines
While most C-Spin openers have at least one option to stack the second bag in a way that may result in a Perfect Clear after 6 lines, the most popular opener used is the ZST Core C-Spin. This continuation for this C-Spin opener is discovered by Chopin. The chance to stack the right side flat with a 3-columns gap and keep any piece (except the T tetromino) on hold is low, but if you stacked it, you may have a chance to get a Perfect Clear. Of course, you may have to sacrifice the T-Spin in order to achieve a Perfect Clear, particularly if the I piece is the remaining piece left.

Particularly for the ZST Core C-Spin, the second bag can be stacked differently by making a 2-columns wide gap beneath the I piece while holding the J piece. Achieve the Perfect Clear by making a T-Spin Single (using the T piece from the third bag), then score the Perfect Clear Double by using the held J piece. If not possible, just make a T-Spin Triple.

Perfect Clear after 8 lines

 * Main article: C-Spin Perfect Clear

Technically, any C-Spin opener can be used if you are aiming to achieve a Perfect Clear after 8 total lines, but the best ones are the ones with a vertical T as they have better chances than those with a horizontal T in the first bag. For instance, the second bag for the TKI Signature C-Spin opener can be placed like the one in the second diagram and there is a chance to achieve a Perfect Clear in the third bag (41.90% for this example).