20G

20G is a term that refers to when the Gravity is set to 20. Since most Guideline-based games have pieces appear on the 21st or 22nd lines of the playfield, they will instantly drop to the bottom in one frame. The term can also broadly refer to any game or mode wherein pieces instantly drop onto the stack as soon as they enter the playfield. Since most modes of many official Tetris games do not set gravity above 15, 20G is typically reserved for games catering to high-level play, or its own separate mode.

Games with 20G modes

Tetris: The Grand Master

Tetris The Grand Master was the game that coined the term for 20G, and one of the earliest Tetris games to make gameplay changes so such speeds could be playable. In TGM1 and TGM2 (Master mode), 20G speeds begin at level 500. In T.A. Death and TGM3's Shirase, pieces always move at 20G, while in TGM2's Normal and TGM3's Easy, 20G activates at level 300 and 200 respecitvely. The behavior of this mode closely resembles if one were to hold up in TGM2 and 3.

Tetris Effect

Master Mode is an Effect Mode within Tetris Effect that plays at 20G. In place of the normal levels seen in Marathon are "M-Levels", which decrease the lock delay and line clear delay for every ten lines cleared.

Strategies

A piece cannot move across other blocks if the playing field is uneven.

Playing field

T moved right

One structure that will allow a piece to move either left or right is a pyramid:

With ARS, every piece has an orientation achievable during entry delay that will allow it to land on the tip of the pyramid -- column 5. From this point, the piece can be moved either left or right as necessary. Having column 5 higher or on equal level with surrounding columns helps maximize the number of moves that can be performed with a given tetromino. Still, the player should make an effort to avoid overstacking in the center.

T.A. Death mode

T.A. Death is a mode made famous by the "Tetris Japan Finals" video that has been duplicated dozens of times on YouTube, featuring instantly dropping tetrominoes. The difference between death mode and 20G is un-noticeable until later stages in the game in which ARE starts to decrease and lock delay is very low. Arika currently hosts a video showing a GM grade in Death mode here.