FOUR

Hachispin (にはち砲)

A TSS → TST → PC opener. Created by player hachispin.

This opener is easy to memorize and covers a large number of possible opening bags because its only requirement is basically an early O. Most often used when you cannot open with TKI or DT Cannon.

There are some downsides: Any misdrop that happens while you're building Hachispin will most likely be fatal. Also, downstacking is not possible until you complete the TST with your second bag.

TSS

TST

There are three ways to do the TST from this shape, which covers all possible sequences of minos from the second bag.

1

If you can do a TST like above, you will have a 69.33% (3494/5040) chance of doing a perfect clear.


You will have a 59.29% chance of making a perfect clear with these two solutions. These are worth memorizing and will always work if you can place a T and Z like the first picture, or if you can put a T and L like the second picture.

Below are the rest of the solutions, and they are harder to spot.

2 and 3

Shown below are the remaining two ways of doing the TST. The second pattern has a low chance (19.21%) of doing a perfect clear, and a perfect clear is not possible for the third pattern. Solutions for the second pattern can be seen here, but they aren't worth memorizing.

T-Spin Continuation

Assuming that your opponent plays at the same speed as you play, Hachispin PC is easily countered by many openers because it starts with a TSS. However, it is very easy to continue with a T-Spin after the TST when you cannot follow up with a perfect clear.

7-2 Stacking

Hachispin naturally leads to 7-2 stacking. Here is an example:

6-3 Stacking

Examples on continuing with 6-3 stacking:



Others

Here are some other examples of how you could follow up.

They can be useful depending on the garbage hole that you have below.

Refer to this page for more examples.

Continuations for TST 3

These are some follow-up suggestions after using the third form to do a TST.


If you get the right pieces, following up with 7-2 or 6-3 Stacking, which is most preferred, is straightforward:


It's tricky when you get an early Z or a late S. For those, try variations of these follow-ups. The TSS follow-up should cover many of those situations.


Tip

Depending on your bag, you can delay doing the TSS and start building your TST for better timing of your attacks.

See Also / References

Openers

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