Loved it! I did my full playthrough/review in video form, which I'll embed below. There are a couple of things I didn't cover in it though that I'd like to briefly touch on here.
First off, any game with puns in it gets an automatic 5-star enjoyment rating from me. I didn't really read the enemy names until I was reviewing my video review, and viole[n]t especially cracked me up.
I also noticed a couple of potential mistakes while reviewing. First off, when spinning tetrominoes, they seem to drift to the left a lot, unlike in actual Tetris in which pieces generally stay in the same spot throughout their fall unless intentionally moved by the player. The other thing I noticed is that health is not sustained between battles. After the battle against the nighthare all HP that was lost during the battle is regained before you face off against the viole[n]t. These may be intentional, but they seemed anomalous to me, so I figured I'd jot them down and mention them here.
Overall, amazing experience. One of the most polished and feedback-intense games I've seen so far and both those things are great traits to have. Keep up the good work!