The Double Triple Cannon Opener (abbrviated as DT Cannon Opener, also known as DT Cannon Opening), is a T-Spin opener that begins with a T-Spin Double, then a T-Spin Triple. This is one of the first openers TKI invented, dating back to the late 2000's decade. The DT Cannon is one of the most versatile openers and can be followed up in almost any style of stacking. DT-REN and DT-PC are thought to be some of the best counters to the dreaded 4-Wide opener.
With the right set of pieces (one of L/J needs to come before S/Z, both if T comes too early) DT-Cannon can be stacked with very few key presses by taking advantage of two-step finesse. Even though a T piece is "wasted" in the stack, this build can be performed faster than many builds that are more piece efficient (such as Albatross or C-Spin), thus making up for the extra pieces placed. In fact, having more pieces in the stack can sometimes be advantageous, because they can more quickly be transitioned into a 4-wide stack or a Tetris stack. The mirror with cannon on the right side uses more key presses, so it should be stacked on the left for optimal efficiency.
Take note that the JZ Base DT Cannon results in the same stack but needs more key presses.
Second Bag
The second bag is usually placed in one of the following ways. Sadly, none of them will work with certain piece combinations involving early T and S pieces (e.g. TSIZ).
Form A (Continuations)
- 10-line Perfect Clear: The most common way results in a flat stack after 3 bags and a Perfect Clear opportunity after 10 cleared lines.
You have a 36.11% PC chance and 9 solutions.
If the Perfect Clear is not executable, then one can often fall back on this Donation T-Spin Double.
If the O piece is placed in the top-right, your PC probability will increase to 74.05% (12 out of all 48 solutions are shown).
- DTDT Cannon: DTDT Cannon, which is called "DT砲の組み替え" (lit. DT Rearrange) in the Japanese community, is a rare way for players to continue a DT cannon with another DT cannon on the opposite side of the board. Just like DT-TKI, the T-Spin Triple that was built on the second bag have to be done early on the third bag. Z also have to come before O.
Here are some other ways to stack:
Form B (Continuations)
- 10-line Perfect Clear: You have many ways to make a Perfect Clear setup. For instance, the last example has a 79.05% PC chance (48 solutions).
- C-Spin / Triple Double Attack: If you can get an early T piece and get a Z piece before S then I, you can make a C-Spin. You may also get a Perfect Clear opportunity after the C-Spin. The Perfect Clear rate is 99.72%.
If the T piece comes late in the third bag but the C-Spin base can be made, you could hold the T piece to do the C-Spin's TST before doing the bottom TST, which then could be continued into a T-Spin Triple Tower. Since only a single piece is needed after making the C-Spin base to complete the TST in the fourth bag, you have a good chance to be able to make a T-Spin Triple Tower without wasting a T.
Form C (Continuations)
New DT Cannon
The New DT Cannon is a DT Cannon loop invented by KMGZ. You will always be able to stack the third bag like this, even if you get an S early. You then get a 38.49% PC chance if going for 10 lines. If that is impossible, then you can go for 14 lines.
- Kaidan: You can use it if L comes before S. Depending on the order of the I, J and O pieces, these two ways are applicable for most bags.
- L → S and I → OJ or O → J (66.51% PC rate, 2 solutions)
- L → S and J → I (53.33% PC rate, 4 solutions)
- Anchor Set: You can use it if J comes before S. Depending on the order of the I, L and O pieces, these three ways are applicable for most bags.
- J → S and L → I (73.02% PC rate, 5 solutions)
- J → S and I → OL (61.15% PC rate, 1 solution)
- J → S and O → L (33.33% PC rate, 1 solutions)
- T-Spin Mini + Tetris: If T comes early, you can use this continuation. The PC rate is 97.86%.
Other continuations
- Perfect Clear followup (DT-PC): There are of course many ways to set up a PC continuation, but this way has a high success rate and is probably the most commonly employed method (as popularized by pro Japanese players like amemiyataiyou100). After the two T-Spins, use the five previews to figure out the PC.
- C-Spin followup (DT-TKI): If you get an early T, get an O piece before I and Z before S, you can make a C-Spin. You may also get a Perfect Clear opportunity after the C-Spin. The Perfect Clear rate is 99.72%.
- Bread Cannon: You only need an S before L in the third bag and the J piece is placed after the T-Spin Triple. In the fourth bag, you need to do the T-Spin Double early in order to finish the stack before the Perfect Clear opportunity (46.83% PC rate).