Good game. I would have liked the ability to instantly place a piece since it gets repetitive the more lines are lost.
Also, I feel the real timeline added is a minus. The fact that pieces are constantly getting closer to the ground, without player input, is already a timer. I think the game would be more puzzle-oriented if a new line is added ever N number of piece placements. Of course, this is just my own person taste and not a suggestion on how to “fix your game.” Your game is really really fun.
You inspired me to make my own Tetris twist.