I thought this was a really clever idea for a game! The presentation and music are solid, too - they're simple and charming, and lend themselves really well to the type of game you made here.
It did take me a minute or two to understand how the game is played, but once I did, everything clicked. I could go either way on the timer - I felt like it encouraged the player to plan before they started moving pieces, but then again, the movement par did the same thing. It does add some depth, though, since you're being judged for both your planning skills and mechanical skills/speed. Plus, a timer would lend itself well to a high score system if you ever choose to integrate one.
One thing that also might make the UI a little clearer if you choose to expand on this: maybe instead of having an asterisk show where the block you're hovering over will go, you can use a dotted line from the object your mouse is over to where it will go if you click on it?
All in all, this was pretty fun!