Yay, made it through all the levels! :D
That's a pretty cool idea, getting to see how the skeleton will move to create the level accordingly. Normally it's the other way around, you see the level and then have to "program" the movement in these kinds of games.
It'd be great if you could see how far the skeleton would move for every command. Maybe have lines on the movement lanes so you could actually plan ahead. Right now it's more like placing a few blocks, see what the skeletondoes and then adjust you level.
Also on the second to last level there is one invisible spike block, I think.
Apart from that, love the visuals and audio.
All in all a really fun game.