Aitch Stacking is a C-Spin opener. It is originally invented by Aitch himself in 2018, but later named by Agent 1568AH in October 2021. Originally, the first bag was stacked with the J piece notch being made first, and therefore the overhang being J or IL from the second bag, but because of stacking problems, the first J piece makes the overhang first, and therefore, the second J piece will make the notch.

First Bag

If the I piece comes early (not necessarily being the first piece), almost all bags will work, but if the I piece comes as the first piece, it is always possible to assemble this opener, but the TKI 3 Opening would be a better choice because one can make a T-Spin Double in one bag.

When Aitch first made this opener, the first J piece is placed where the notch would be made. However, because of stacking problems, Agent 1568AH changed the placement of the first J piece by placing it on the overhang first. So, if you can stack the former, stacking the second bag would be easier; otherwise, stack the latter.

The overall setup rate when the J piece was made as the overhang and also counting its mirrored opener, is 75%. If the J piece was made as the notch first and also counting its mirrored opener, the setup rate is 68.57%. The mirrored openers are not shown for simplicity.

64.72%

62.54%

Second and Third Bag

All stacks here will be shown if the first bag was stacked with the J piece being the overhang.

Perfect Clear

Ideally, you should be able to stack one of these setups for a chance of getting a Perfect Clear in the third bag.

Standard setups

These setups were chosen by Agent 1568AH and he also discovered setup F.

• Setup A (48.33% setup rate, 96.90% PC rate, 9 minimal solutions): This is the most ideal way to stack the second bag for a chance of getting a Perfect Clear in the third bag. Furthermore, one can use an S-Spin to place the S piece, if the O, L and Z pieces were already placed.

• Setup B (66.67% setup rate, 95.79% PC rate, 24 minimal solutions)

• Setup C (24.44% setup rate, 93.02% PC rate, 7 minimal solutions)

• Setup D (41.11% setup rate, 91.19% PC rate, 6 minimal solutions)

• Setup E (70% setup rate, 91.03% PC rate, 19 minimal solutions)

• Setup F (52.86% setup rate, 85.28% PC rate, 8 minimal solutions)

• Setup G (40.63% setup rate, 80% PC rate, 7 minimal solutions)

• Setup H (36.51% setup rate, 79.96% PC rate, 8 minimal solutions)

• Setup I (45.56% setup rate, 62.34% PC rate, 4 solutions): Normally, setup F should be used intead of this, but for some cases this must be used instead of the former.

• Setup J (66.67% setup rate, 40% PC rate, 3 solutions)

Supplemental setups

• Setup 1 (23.81% setup rate, 97.98% PC rate, 19 minimal solutions): If the I piece come before Z also hold the O piece at the same time, the most ideal setup can be stacked. If you must place the O piece, it should be placed on the overhang (setup B).

• Setup 2 (21.43% setup rate, 97.42% PC rate, 10 minimal solutions): If you must place the Z piece, you should be able to assemble setup A or G.

• Setup 3 (24.76% setup rate, 96.07% PC rate, 21 minimal solutions): If you must place the O piece, use setup E.

• Setup 4 (1.90% setup rate, 94.74% PC rate, 18 minimal solutions): It is not possible to score a T-Spin Triple and get the shape shown in the second diagram. On the other hand, there is a chance to get a Perfect Clear after 6 or 8 lines. In this case, after the T-Spin Double, place the Z, then S, and then L to clear a line.

TSD + Single

6-lines PC

8-lines PC

Compromise

If it is impossible to stack any of the Perfect Clear setups above, you can always stack one of the two ways below, depending on the order of the L and O pieces. A T-Spin Triple Tower can be stacked after the T-Spin Triple in either case.

See also

• Triple Double Attack
• Loyal TD - Another C-Spin opener with Perfect Clear continuations
• Mountainous Stacking - A separate opener with many Perfect Clear continuations

External links

• Post about 8-row Perfect Clear Setups (see C-Spin)