Skimming

Skimming is a method where a player does a non-Back-to-Back line clear to make the stack more favorable. This page will focus more on skimming used for offense in the current guideline Tetris.

Introduction

In modern Tetris, skimming has a couple of utilities:

As mentioned before, the point of skimming is to lead the field into a more favorable stack. This gives the player more choice on how to place the subsequent minos, such as building a TSD.
Line clears mean a lower overall stack. A lower overall stack implies the ability to accept more incoming garbage lines. This is good for temporary defense.

However, skimming has three critical drawbacks:

The player loses Back-to-Back.
Non-Back-to-Back line clears inherently have lower attack efficiency.
The player has to deal with an added line clear delay.

Therefore, skimming is not optimal for attacking and should be reserved as a defensive measure.

Identical Function Minos

Due to how minos are structured, there are several groupings of minos that serve identical functions for skimming.

credit to mkomiz for the first two diagrams

Basic Skimming

Tetris

Looks like this. You can achieve the same field with T or J.

TSD

The most commonly used TSD skimming looks like this. You can achieve the same field with an S instead of an O. Not too bad because the double line clear sends 1 line, and the TSD restarts Back-to-Back.

credit to kazu for the example

These are some other skimmings that are relatively often used, mostly as a compromise for not having the right pieces.

Here are some other situational setups.

Named TSD Skimming

These are some named skimming techniques that result in a TSD. You'll probably encounter these every once in a while.

Pierce

貫の技法. This skimming pattern with an I is useful to know.

For this example, you would be rotating the I mino counterclockwise twice.

WC Plowshare

WC鋤の刃. Useful when you need to do a TSD as soon as possible, but you don't have the right mino to complete the TSD shape in certain situations, e.g., in a field like below where you don't have an I coming soon.

You could also turn this into a TSS donation technique, but this would only be applicable in pretty specific situations.

credit to Circu1ation for the example

Dejavu

デジャヴ. Mostly used for downstacking instead of building a TSD because a Tetris is usually a better option if you're trying to attack. Line clearing this way is also used in some perfect clear solutions, such as the ones for MKO.

Consider it in a situation like below where sliding in the L would take too long. Since this soft drop is tricky, people often miss it and do this technique involuntarily anyways.

Emergency Skimming

These are used when you have to lower your stack ASAP.

Aborting TSD

Used when you don't have a T coming soon to do the TSD. A common situation would be having to do this instead of completing the second TSD of STSD because you have to get down quickly.

Needless to say, using an I here to clear lines would result in a bad stack.

Aborting TST

Works even when you have a TD setup.

Switch

スイッチ. Used when you are at the very top of the board. This preserves the TSD slot and an overhang while allowing you to accept 1 more line. You can also use it to extend combos to combo into a TSD.

FOUR