the retry prompts are a nice touch, it's amazing to see that this game's basic mechanic is so good that it already feels like a complete game even with the smaller level selection of this dev time frame, the only complaints i can think of is the lack of indication of if the windows can move in specific directions and the last level being underwhelming, and that's not even a game specific issue!
with the time for a polished art style, level design and maybe a level editor this could easily go on storefronts in no time! 10/10 mechanics