Oh, nice puzzle game!
Feels though like it didn't get much harder after several rounds. This probably fits a time-killer kind of game, but otherwise you can maybe expand by gradually making the field larger, or increasing the number of requirements, or both.
I'd maybe also suggest making a more clear indication of where each piece should be (e.g., you can draw its silhouette on the board) + I'd add some visual indication when a piece is on a desired spot (e.g., make it glow). Otherwise it may become too hard to play without sound.
Anyway, I enjoyed playing a lot. Nice game!