I don't play Tetris at all, but I have watched some Suisei Tetris streams, so I have a general idea of how classic Tetris should be played.

1. No WASD controls.
2. In classic Tetris, when you clear the line, the blocks above fall down. In your game they are always static, this alone increases the difficulty of the game, and on top of that the falling speed of the blocks also increases. IMHO you should keep only one of those, either static blocks with constant falling speed, or either make all blocks magnitize to the center while increasing the falling speed.
3. I didn't like that you can't attach blocks by moving in the direction of static blocks. Like, if you moved it to the point where there are no blocks on the way, you can't do anything.
4. Maybe instead of a rectangle, make that you have to build a line in each direction, like playing 4 classic Tetris games at once.

This is mostly about the classic mode, I've played other modes, but I'm not a big fan of Tetris, so I can't give any feedback about them. But overall the idea is good.