This is a very interesting take on a classic game. It is very forgiving on what constitutes a complete row which makes the game more enjoyable as I can spend my time panicking over the newest piece rather than shifting old ones to be perfectly aligned.
I'm not sure why you made the walls holding in the pieces slowly drop. That's a very interesting mechanic, but as it is now, it's pretty much an instant loss once they drop below a certain height. I am guessing the lenient row removal let the game go on for way too long so you needed a new lose condition. That's fine, but I feel like it could have been more forgiving. Maybe replace the walls with a force field that kind of pushes blocks back but not enough that you can just freely fling them without worry. That way the game kind of enters hardcore mode after a time but is still playable.
Just a suggestion. I had fun with the game in it's current state, so nothing really needs to be changed. Thanks for submitting it!