Mountainous Stacking

Mountainous Stacking is an opener that may result in a Perfect Clear chance after the T-Spin Triple in the second bag. It is created by Agent RO in mid April 2021.

This opener has the same piece depenencies as Ito Cannon and Syrup Stacking. Like them, you need an early I and L. The difference between Mountainous Stacking and those two setups is that the first J piece will be used in various orientations to accommodate the sequence of your second bag.

First Bag
You can use this opener if you have an early I and L in the first bag. The J piece (L in the mirrored setup) is in Hold.

Second and Third Bags
In the second bag, you can get a Perfect Clear in these 3 cases, but there will be a lot of piece dependencies, especially for the third case. If any of the 6 ideal cases is not applicable, the compromise is always available.


 * S → O and J → I / S → JO (98.85% PC rate, 65 minimal solutions)


 * O → I and S → JL or L → S (96.87% PC rate, 15 minimal solutions): For the second diagram, the first J can be placed on the very right and the second J is used for the overhang.


 * I → O and S → JL or LJ → S (95.91% PC rate, 29 minimal solutions): The first J piece is used on the left first.

If any of the 6 cases cannot be applied, use the compromise below (44.80% PC rate).

In case you cannot achieve a Perfect Clear with the compromise, you will always be able to stack the second bag in these 2 ways, depending on the order of the O and Z pieces, even if you get an early I piece.

If the O piece comes before Z, you will be able to stack the third bag as follows, then you can always stack the fourth like so, which leads to a Perfect Clear chance (100.00% PC rate).

If Z comes before O, you will be able to stack the third bag as follows, then you can always stack the fourth like so, which is a Yoshihiro SD setup.

Mountainous Stacking 2
Mountainous Stacking 2, by Agent RO, is the successor to Mountainous Stacking. Like its predecessor, it is mostly used as a Perfect Clear setup. However, unlike its predecessor, the latter has no piece dependencies (the mirrored setup is also accounted) and there are fewer case differentiations in the second bag. This opener is fully developed in early May 2021.

Like Gamushiro Stacking, you can always stack this opener (including the mirrored setup). One advantage is that lowest possible PC rate is 97.94%. One disadventage is that you must softdrop the Z, especially for the final 2 ways of stacking the second bag. Nevertheless, this is a good alternative to Gamushiro Stacking.

The L piece (J in the mirrored opener) is in Hold.

Second Bag and later
Choose one of the 3 ways depending on the order of the S and O pieces (the I piece is also considered in the first way). In the third situation, one can make a Perfect Clear after 14 total lines.


 * O → SI (99.09% PC rate, 63 minimal solutions): Use this way if you get an early O, but not if it comes after I.

If you choose to forgo the Perfect Clear, you can use Mechanical TSD if you get an early J.


 * S → O (97.94% PC rate, 19 minimal solutions)


 * I → O → S: The third bag can always be stacked even with an early I piece, and fourth bag can always be stacked, leading to a Perfect Clear chance (99.72% PC rate).

Extra way

 * LI → S (96.90% PC rate, 13 minimal solutions): This is an extra way but for bags such as TIOLZSJ, this can be used instead of the third route.