Speaking as a fellow game develeoper, considering it was made for a game Jam and in a short time, it's pretty good. There are some obvious flaws in general quality and polish, but I won't discuss these because you probably didn't have time to sort these little things out. I won't take them into consideration into my final score either.
So let's talk about game design, which is the most relevant aspect for you, and the one which my score is based upon.
I played about 15 stages before getting bored with the game, and while playing it, I noticed a few critical flaws in game design which I think should be addressed to make the game more enjoyable.
1 - Some stages are too big. I noticed that for some of the stages, I kept just repeating the same patterns over and over again just to fill up the stage. Only a couple of the moves I made were actually critical for the success or failure of the stage, and after these were made, the rest of the stage was just repeating the same moves over and over to fill up space. What I mean with this, is that stages without many solid tiles in it should be smaller to avoid useless repetition, which causes boredom in the player.
2 - An Undo button is sorely missed. On many stages, while making the boring repetitions necessary to fill up all that space I found myself slipping and pressing the wrong key, instantly losing any chance of completing the stage properly, and having to repeat the stage and do those boring repetitions even more!
3 - Talking about finishing stages, lets be fair. There is no purpose at all for the 1~3 stars system. Completing the stages with 1 and 2 stars is just way too easy, to the point of completely removing the fun and the objective of the game. I feel the only reason it was put in there was to prevent the frustration some of the levels' design caused on the players (again going back to points 1 and 2). If proper level scale and difficulty progression was there, you could easily remove this system all along and make it so the only way of progressing is completing the level 100%.
4 - The tutorial screen is way overcomplicated. The information is presented in a confusing way, with too much text. Try to make use of more visual ways of presenting information next time. As long as the basic mechanics are illustrated, you don't have to describe absolutely everything. Let the player discover the minute details by themselves, or present the other mechanics (such as keys) slowly, as they appear on the game, not all in one screen.
Anyway, now that the bad stuff is out of the way, time to praise what is good in the game. The concept of the game itself is simple and elegant. I can easily see this working out to be a great game with some proper polish and some rework on the general Level design. The music is good, too. Fitting and relaxing.
If those flaws I've mentioned were to be addressed, I could easily see myself losing an hour or two to complete this game 100%.
Anyway, keep up the good work, and good luck on your future games!