I would recommend doing a click based undo system, as in, when you click on a piece it gets returned.
Also, the last level is a b*tch. Ended up not using one piece.
Dragging the soul out and hitting the scrollscreen and then clicking on the spawn will cause the soul to bug over the original making it hard to click the original image
Kinda bad, the game itself has no pattern recognition, it has a perfectly set out pattern. I've seen many game where i placed the shapes on the wrong side of the "light"