This game is really original and perfectly fits the theme, but in practice, it feels really tedious, mostly due to the number of inputs to add or remove blocks to progress through the level.
The purpose is a bit defeated when you also understand that you can take the right amount of block to the end, then build your shape there.
I think your game would have greatly benefited from a more "puzzle-oriented" level design, maybe with blocks you can and cannot grab, in a more closed space.
Overall, great idea, but would be better fitted for a different context.