Pretty fun, with flaws.

If everything is going to be based on the numbers, make them look better for one thing.
I like a challenge, and this game provides one.
However, making more minigames, and this one being kind of like a 'boss' level could be something to make the game more fun.
It works, and pretty good at that.
I like how the music is not very hugely noticeable, so the loop doesn't get very distracting.
The buttons are really nice. I think you could put the whole bottom bar in a wooden oval-shaped box around it would look cleaner.
The background looks pretty bland, as do the numbers, as stated earlier, which need some touching up.

It works

The game works as it's supposed to, for the most part. I was noticing some glitching in the beginner puzzles in the upper slots in which images of initial blocks were getting imposed on the screen. The game does what it says and seems like it would be good experience for the author, if sketchy and uninspired at the moment. Keep working at creating, try to think more creatively.

LOL!!!

that was so refresh'in my mind from those n00b collabs there