For me, this game has non-sense difficulty. I've done my best for trying to finish one time each level. But i didn't succeed. Your game has all for being a great game : great music, funny graphics and animations. But game constraints are too much restrictive.
I will not talk about "Move" level because it's hard, but if I had more patience, I could finish this level.
Now, "Stack" level isn't winnable. You have 4 constraints : rope movement, turret shots, robot moving and box counter ! When one of these constraints disturb you, you have to reset the level ! And it's very hard when you have 5 boxes stacked to not being shot by the turret. So you reset and reset again.
In my opinion, the box counter can be dropped. Because with that, your game is unplayable.
And for finishing this review : i didn't find the "pause" button, the "go back to main menu" button and the "retry level" button. It can be good if you add them ;)