[temetnosce]

The rabbit hole of Tetris goes pretty deep and most people who implement their own version of Tetris don't realize that there are modern rules and requirements for how the Tetrimino blocks get previewed in the next window, drop, move, lock, rotate, and collide when rotating.

The modern system/rule for rotation and collision is called the Super Rotation System which was made by the Tetris Company. This allows for techniques such as T-Spins in which a T Tetrimino (the one shaped like a T) can be fit into spaces that wouldn't normally fit in which result in extra points. Without these rules or requirements implemented, your game cannot be officially licensed by the Tetris Company and get the Tetris branding.

In "Tetris: The Grand Master 3 - Terror Instinct" (the one with invisible blocks at the credit screen) had two modes, classic and world. World uses modern rules which is considered much easier with the Tetris Company rules as mentioned above.

[stormbrew]

Sadly there'll probably never be a tgm4 because TTC has done the allegedly impossible and successfully copyrighted a game concept so that it's not just "this is what modern Tetris is usually like" but "this is the only kind of Tetris that is allowed to exist".