From Hard Drop Tetris Wiki
Perfect DT (Perfect Double Triple / パーフェクト DT) is a setup invented by a Japanese player named Yuu. It resembles a TKI 3 Opening but with the L placed upright on top of S which makes it looks kind of like a "wing". Usually made to achieve a T-Spin Double which could then be continued with T-Spin Triple without wasting a single T and usually ends with 8th row Perfect Clear. This is one of the only discovered setups that could achieve 8th row Perfect Clear without wasting a single T (other setups like Albatross Special and Pelican could only do Perfect Clear after 10 cleared lines). This setup could be made with an early I and S have to come before L. Perfect Clear after 14 lines is also possible.
First Bag
Mirrored Setup |
Normal Setup |
Second Bag
T-Spin Triple
This setup is usually continued by T-Spin Triple. Notice how JI and LO could be swapped which increases the chance to score a T-Spin Triple without wasting a single T. It uses a very unusual overhang but it works nonetheless.
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If J comes early but Z comes before I, one could still create a T-Spin Triple with S placed vertically on top of L.
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T-Spin Double
If it is impossible to make a T-Spin Triple on the second bag, one could still continue with a T-Spin Double. The chance to stack this one is 100% because O, S and Z can be stacked in any order.
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The O, S and Z pieces can be stacked in one of four ways:
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It is possible to continue the T-Spin Double with Type 1 ST Stacking. Here is an example:
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Third Bag
Normal Setup
If you did the normal setup, then there is a 75.87% chance to do a Perfect Clear after 8 lines. 15 of the 18 solutions are shown. Link to 18 solutions: [1]
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Mirrored Setup
On the other hand, if you do the mirrored setup, then there is 74.33% chance that it could end with 8th row Perfect Clear. The probability is lower because fewer I-Spins work there.
Link to 18 Solutions: [2]