Definitely a very original setup and a cool twist on the sort of "out of control" puzzles you normal find with ice puzzles and stuff. The lighting was a cool way to handle interaction and there's definitely some interesting puzzles and chances for more interesting puzzles.
Though I do have to say the controls did get a little frustrating, mostly with having to reset everything whenever I mispressed a key, and being locked to 4 directions with no diagonals (especially considering some of the shadow angles).
It all really became a problem on the final level where I ended up feeling like I was losing a lot more to the controls rather than the actual level. Since I knew a few solutions, but everytime I tried to do them either I would just barely get out of the light and have to try again, or I would end up slightly pushing a box too far or not far enough and have to restart (trying to be unclear cause final level and spoilers etc.)
To be specific tho, and spoilers if anybody hasn't played and doesn't want the final level mentioned. Pushing the battery from the top behind the door became a challenge because of the fact that I needed to either line it up with the box or push it against the wall. Lining it up with the box at the bottom of the screen looked plausible because I could just push the box out from under it and circle around.
Except the players hitbox was big enough to push both of them. Leading to the only way for that to be viable to be for me to circle around trying to avoid the shadows to get on the other side. Which posed it's own issues since walking on diagonals isn't possible and the shadow was a diagonal. Leading a lot of attempts, and a lot of just barely hitting the shadows.
As for the option that seems to have been taken in the gif on the page, trying to get the left box onto the button worked but obviously that blocks the method of pushing the battery all the way along the bottom wall. Which meant that, from what I could tell, the best option was still to find a way to push the battery against the box for leveling it with the light.
Someone else already suggested a rewind feature, which I definitely think would be quite useful. I'd like to recommend some sort of more grid based movement for the puzzle pieces though. Since getting the battery or boxes etc. just out of line led to a lot of issues.
P.S. I did actually finish the final level, by cheesing it and just having the bot walk through the darkness over the button and into the final room. I was really hoping to beat the level though.