This is a very interesting concept and super fun to play!
I encountered a couple of bugs where two shapes moved onto the same tile and drag and drop stopped working, but apart from these the experience was flawless.
It's cool how the player is able to consistently defeat any shape in a 1v1, but once more shapes appear it gets more and more difficult.
At first it seemed like the tetrominoes weren't necessary, but soon i realised that using them helped a lot. I started saving powerful ones for useful situations and it really got me to make some tough decisions.
All deaths felt like they were my fault and I think I could have been able to avoid them with better strategies.
Good Job!