In each of the big game types (SRS, TGM, TGM3, etc), does the O block "rotate"? That is, do you hear a rotate noise and are any timers reset when the rotate button is pressed? Thanks for the help!
In SRS, it rotates and resets lock delay when doing so. In the TGM series, it rotates (as evidenced by the metallic IRS sound), but rotating it has no effect whatsoever, except in TGM2 where it counts towards the RO (rotation) medal.
In every official game that I've played, the O tetromino rotates, and you can hear it, and if the game features tweened rotation animation (Tetris & Dr. Mario; The New Tetris; Puyo Pop Fever; Tetris DS Touch), you can see it. But only those games that use multi-colored tetrominoes let you see any net effect of O rotation. Bombliss, The Next Tetris (and TW Sticky), Lumines, Puyo Pop Fever, and Tetris DS standard multiplayer with items are the ones I can think of. The Carbon Engine used in some of my clones could be configured not to make the rotation sound for O tetrominoes.
Well, rotating the O piece in the TGM games count as a rotation.. I seem to recall Colour Thief mentioning that the only thing he needed to change to get the RO medal was to rotate the O pieces.