9: Imperial Cross

Tutorial Videos

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The Basics

Imperial Cross is a double T-spin double method, like a Fractal.

Diagram Set 9-1

It opens up many opportunities. Here is the proper finesse to use it:

Diagram Set 9-2
1	2

This shows the basic shape of an Imperial Cross.

This involves putting a T into the cavity. Rotate it vertically, creating a T-spin double line clear. The cleared lines are separate.

This leads to the resultant pattern of a basic T-spin double.

This involves spinning a second T-spin double to complete the setup.

Mid-Game Chances

Here are the main methods of constructing the Imperial Cross. They are not exhaustive:

1. Upgrading from a T-Spin Single or Double

Imperial Crosses are most easily created by upgrading them from T-spin singles:

Diagram Set 9-3
1	2

Spot this T-spin single chance.

Fill up the left side (this is not exhaustive) to create an Imperial Cross.

The above step 1 can be upgraded into an Imperial Cross.

You can also upgrade a T-spin double to an Imperial Cross:

Diagram Set 9-4
1	2

Spot this T-spin double chance.

Upgrade it by adding an overhang to create an Imperial cross.

Hence, an Imperial Cross may share the same opportunities as a normal T-spin single, double, or triple. You can simply upgrade them into an Imperial Cross.

If you can spot the below’s A or B, you could have likely made an Imperial Cross instead of the following T-spin double or T-spin triple setups:

Diagram Set 9-5
A	B

A T-spin double.

A T-spin triple.

2. General Ways

Here are general ways to construct both sides of an Imperial Cross.

Constructing the ‘Short’ Side

Diagram Set 9-6
A	B

The above shows ways of creating the ‘short’ side or lower base of the Imperial Cross setup.

Constructing the ‘Tall’ Side

Diagram Set 9-7
A	B

The above shows ways to create the ‘tall’ side, or the overhang, of the Imperial Cross setup.

3. Upgrading Certain T-Spins in Some Garbage Hole Locations

In the mid-game, you can get the following T-spin situations with a hole beneath them. Depending on the location of the hole, you can sometimes upgrade them into clean Imperial Crosses:

Diagram Set 9-8
1	2

Spot this T-spin double chance. Note the garbage pattern below.

Fill up the rest to make a clean Imperial Cross.

Imperial Crosses are optimal in the following situations:

Diagram Set 9-9
1	2

This T-spin double is unclean. After the line clear, the overhang will block the next hole.

Hence, this is the perfect chance to upgrade it into a clean Imperial Cross!

Noticed how a dirty setup is turned into a clean Imperial Cross in the last 2 diagram sets? After each diagram set’s step 2’s 2 T-spins are complete, no dirty overhangs block the next hole, making them clean.

Important Decision-Making

Imperial Crosses are generally dirty, and I often give them up in favor of other cleaner setups. Regardless, there are cases where they are clean and optimal.

It is my least favorite canonical setup, and I use it only when no better one exists.

1. Choosing between Imperial Cross and Fractal

Fractals and Imperial Crosses often have the same mid-game opportunity. Either can be more valuable than the other, depending on the situation.

Fractal is always better since it needs no quadruple rotation to kick one of the T pieces in. It also does not shift or block the garbage hole. However, if the pieces do not arise to build the overhang for Fractal, you can opt for Imperial Cross instead.

Here is an illustration:

Diagram Set 9-10
1	2

You can easily chain clean T-spin doubles by spamming Fractals and using LST stacking.

What happens if you instead use Imperial Crosses in the same scenario? Behold:

Diagram Set 9-11
1	2

This starts with the same field as the last diagram set.

Making an Imperial Cross shifts the hole’s location by one to the right in step 4. This breaks LST stacking. The protruding overhang from the S piece must sometimes be skimmed off to expose the next garbage hole.

Therefore, I typically advise using cleaner T-spins, such as Fractals, rather than Imperial Crosses.

Because of the overhang, Imperial Crosses are tricky to do. Many should be given up because they lead to uncleanliness.

Below are 2 more real mid-game examples of how to make clean Imperial Crosses.

Diagram Set 9-12
1	2

The additional hole below the Imperial Cross makes it clean after the first T-spin double.

Diagram Set 9-13
1	2

This is good, too, because the follow-ups are clean.

Conversely, one should avoid these dirty Imperial Crosses and instead use Fractals:

Diagram Set 9-14
1	2

This is an Imperial Cross. Note the location of the garbage hole beneath it in column 5.

The first T-spin double concludes.

Alt. A

The red-circled overhang blocks the future garbage hole in column 5.

A better alternative would be a Fractal, as it is cleaner and does not block the next garbage hole.

2. Using Imperial Crosses to Sustain Back-to-back Bonus

Earlier, I have already explained how Imperial Crosses can sometimes be made clean. But that is not all!

Doing this has the extra perk of being easier for the player to sustain back-to-back bonuses, because no overhangs must be skimmed:

Diagram Set 9-15
1	2

This T-spin double will leave an overhang over the next garbage hole if the T-spin double finishes.

However, the player uses an Imperial Cross.

The first T-spin double concludes.

The next T-spin double is clean, as the original garbage hole location is not shifted to the left or right. The hole is exposed.

This Imperial Cross is clean and sustains a back-to-back bonus since you do not need to skim.

Continuations and Follow-Ups

Despite their limitations, Imperial Crosses can be followed up cleanly to make more T-spins.

1. T-Spin Double Follow-Ups from Overhang Heights

Imperial Crosses are best when their overhangs are 2 blocks high, as it can lead to LST stacking continuations below:

Diagram Set 9-16
1	2

This is an Imperial Cross.

The 2 T-spin doubles in it conclude.

You are left with this shape.

A straightforward LST stacking continuation happens.

Thus, the 2-block-high overhang makes it almost effortless to make the next T-spin double.

2. Stacking Imperial Crosses

Imperial Crosses can be ‘delayed’ by stacking over it like this:

Diagram Set 9-17
1	2

An Imperial Cross is made without the overhang to complete it.

The player stacks a T-spin above the Imperial Cross pattern.

He then completes the T-spin double line clear.

This exposes the bottom Imperial Cross pattern, where he builds an overhang to complete it.

Knowing this method slightly improves one’s T-spin offensive power and foresight.

3. C-Spin Follow-Up

If you perform the T-spin double in the following manner, you can easily follow it up with a C-spin:

Diagram Set 9-18
1	2

An Imperial Cross.

Make the first T-spin double in this orientation.

You get this shape.

Which can be easily followed up with a C-spin.

4. Vertical T-Spin Double Follow-Up

The next step below corresponds to diagram set 9-18’s step 3, showing an alternative. You get a T-spin double:

Diagram Set 9-19
Alt. A1	Alt. A2

This is the same shape as the last diagram set’s step 3.

You can make this strange T-spin double. Rotate the T piece into the cavity until it has the vertical orientation shown.

This T-spin double is slightly awkward as it is vertically resolved. However, the resultant shape is sometimes difficult to follow up on.

Advanced: Spliced Imperial Crosses

Imperial Crosses can be spliced. This means you can insert another T-spin inside it. However, this is an advanced and highly risky technique.

1. Nil-Cross (Vela)

The setup below is a Nil-Cross. It inserts a T-spin triple into an Imperial Cross:

Diagram Set 9-20
1	2

A Nil-Cross is ready. The first T-spin is a triple.

After the line clear, you get a typical Imperial Cross.

This is how to create it mid-game:

Diagram Set 9-21
1	2

This is the easiest Nil-Cross mid-game chance. It gives 3 T-spins.

Just put S and L like this and make an overhang. Voila!

This method is practical for competitive play if the player is skilled enough. I have seen high-level Korean players use them in guideline Tetris games.

2. Black Cross (Centaurus)

A Black Cross is an Imperial Cross augmented with an additional T-spin double.

It grants 3 T-spin doubles:

Diagram Set 9-22
1	2

A Black Cross.

The first T-spin double clears horizontally.

This leaves a standard Imperial Cross.

You can create it this way, by stacking it over a partial Imperial Cross shape:

Diagram Set 9-23
A	B

If you can spot a mid-game Fractal chance (in lavender), upgrade it with the above upstacks into a Black Cross (It has 3 T-spin doubles inside).

Likewise, I have seen high-level players use this in competitive setups. However, it is best aborted for fast-paced, unofficial Tetris games like TETR.IO, where there are no line clear delays.

3. Spliced Black Crosses

Black Crosses can also be spliced by inserting a T-spin triple into them like this:

Diagram Set 9-24
A	B

The easiest way to splice (insert) Black Crosses with inserted T-spin triples is to upgrade Fractals (lavender) with the above common upstacked placements.

Typically, this is a gimmicky method, and I do not advise using it for competitive play.

In a Nutshell

Imperial Crosses are not as clean as other setups. Hence, using them boils down to placing their follow-ups so that their overhangs are managed properly and cleanly.

Pros and Cons
Pros	It is an excellent alternative to Fractal if the pieces do not come for the Fractal. It can be chained multiple times for many T-spins.
Cons	Imperial Crosses shift and block out the Tetris hole, misaligning it.