[dragontamer]

Not "some variation", but "THE variation", SRS Tetris. (Super-rotation system).

Tetris is owned by the Tetris Corporation, and SRS Tetris is their standards applied to the game. The fact that SRS Tetris is missing from this entire page is... a BIG red-flag to me.

SRS Tetris is the style used in official Tetris Games sponsored by the Tetris Company: Tetris Friends, Tetris Ultimate, Puyo Puyo Tetris, and "The Tetris Effect".

[trevyn]

Who owns the Tetris Corporation?

[bluntfang]

seriously, you could've googled it. https://en.wikipedia.org/wiki/The_Tetris_Company