Hyper Fractal

The Hyper Fractal is an easy recursive setup for multiple T-Spin Doubles. Recursive in this case means, that after each T-Spin Double the board is in a similar state to set up the next T-Spin Double. It was created by BiseSim.

Introduction
For every piece there is a preferred spot where one wants to place it. The S, Z and O pieces should be placed on their stacks, the J pieces are placed in the well on top of each other, The L piece is used to create the T-shaped holes, the I pieces should be placed in pairs on the O, S or Z spots and the T piece is used for the T-Spin. When everything comes together it could look like this:

First steps
The base of the Hyper Fractal's main stack is made with an I and Z piece.

The board is now divided in four partitions:


 * On the left is a 4-wide well that will be filled with J and L pieces to create the T-shaped holes and the T pieces to clear the T-Spins.

The main stack is divided into 3 partitions:
 * An O-stack
 * A Z-stack
 * An S-stack

For the I pieces, one can place them in pairs on the O, S or Z-stacks or clear them horizontally in the 4-wide well.

However, there is another problem. At the start of the game, one has placed too few pieces to start farming T-Spin Doubles and keep the Hyper Fractal going. Therefore, they need to build the main stack first so that there will be enough "fuel" for the machine. That means they need to figure where to place the L, J and T pieces on the stack.


 * L and J-pairs can build rectangles and can be placed on the O-Stack or a larger rectangle with the L, I and J pieces.


 * The T piece is slighly tricky because it interacts with the S and Z-stacks. Placing a T-piece on the S-stack transforms it into an Z-stack and vice versa. That means one needs to place the T pieces in pairs so that after the placement of both T pieces they have again an intact S and Z-stack. Note that it does not matter where they place the two T pieces. They can stacked up in pairs on either the S or Z-stack or one T piece each could be placed on both stacks, the end result will always be an S and Z-stack that is accessible, but the stacks might have switched places.

In this example, they now stack the J pieces inside the 4-wide above each other. That means it is recommended to place 2 L pieces on the main-stack because that way they ensure that they always have an L piece functioning as an overhang. Together with the other considerations the first 14 pieces could be placed like this:

Note that these are not really the first 14 pieces because in the example they already placed an I piece and Z piece first but the main idea remains the same. Summary: It is recommended to place 1 or 2 pairs of T pieces and more L pieces than J pieces on the main-stack before starting the Hyper Fractal loop.

Starting The Loop
The main trick of the Hyper Fractal is spinning the L pieces between the J piece stack. It is better to spin the L piece in a position so that it looks like an actual "L" when placing it in the stack and rotating it when it comes in contact with the first block or the floor. Placing the L piece "upside-down" could lead to it getting stuck and not able to rotate anymore.

If the main stack is high enough, at least 3 or 4 J pieces are placed and 2 L pieces are already rotated in the J-stack to create 2 T-shaped holes it is time to start the loop. Now one spins every L piece in to create another T-shaped hole and every T piece to clear the T-Spin. Make sure to keep the main stack relatively flat while building. So when possible, the pair of I pieces should always be placed on the lowest partition of the main stack.

But keep in mind, that it would be preferable to hard drop the L piece in order to maximize speed. Do not forget to place the J after it or else there is no T-Spin and trying to clear with a T piece only results in a double line-clear.

Main Stack Management
Knowing how to build the main stack in different ways is very helpful, because the Hyper Fractal is burning the "fuel" of the main stack. With each loop players clear 30 blocks (L-Spin line clear + T-Spin). But all 7 pieces together add only up to 28 blocks. So the main stack runs out of fuel 2 blocks per loop. That means they need to use some of the J, L and T pieces on the main stack after a while. In order to do that it is also important to know how to stack the other 4 pieces so that the main stack does not become too uneven.

There are 2 possible configurations of the S and Z stacks:

Here are some further stacking options for these cases.

The O, S and Z pieces can transform the open configuration into the closed configuration:

The same result can be achieved with either two S or Z pieces.

The closed configuration can be preserved in this way:

The closed configuration can be transformed into the open configuration in this way:

Alternative Setups
Similar to the example used at the beginning, there are other ways to create simple setups for the Hyper Fractal.

Keep in mind that every setup can also be mirrored, but not only that. Because the 4 partitions can be stacked independently and do not need to interact with each other, every permutation yields also a valid setup. Furthermore there are always two main methods to fill the well by either stacking the J or the L-pieces.

These considerations lead people to the realization that there are at least 48 alternative setups, including the original example. By understanding the modular nature of the different stacking setups it is easier to see how to transition into a Hyper Fractal in a variety of situations.

Here are a few examples how the O, S and Z-stacks could also be placed:

The T-Opening
One other way to setup the Hyper Fractal is by placing a single T piece that functions as the base for the S and Z-stacks.

One disadvantage for this setup is that it makes the S and Z-stacsk asymmetrical and therefore rules out some easily accessible stacking options but other options become available. In fact, it is possible to transform the 6-wide main-stack from a stack with an asymmetric S, Z-stack to a symmetrical S, Z-stack and vice versa. The key is placing another T piece. Here are a few examples:

7 Piece Opening
For an opening, it is important to know how to use all 7 pieces of the first bag. An opening of the Hyper Fractal should focus on building the main stack first.

It has an asymmetric S, Z-stack but that can be fixed. For example like this:

J, S, Z-Skimming
One useful technique for balancing the stack is J-skimming (L-skimming in the mirrored setup) if the J-stack is too high. By rotating a J piece instead of an L piece, it creates a shape that can be cleared with either an S or a Z piece. That operation just clears a J piece from the stack so the board will be in the standard state again. It is also possible to place the S or Z piece first and skim with J or L piece later.