Took a few tries before I finally really understood how to play. Seems interesting, but a couple things:
It might be nice to also have keyboard options for rotating the pieces - the mouse wheel can be finicky, and trying to click the rotate buttons can be frustrating (I can imagine it gets worse, when trying to do it at speed with the delete button right there as well).
There seems to be a bug, and I wish I could give you good reproduce steps for it, but I can't see exactly when it's happening, but the level just kills itself. It might happen when I'm placing pieces too quickly - but that's not consistent, so I feel like it might be something else. But I can just start a level, place a few pieces, and have the level end.