I absolutely love the idea, and it's a really unique way to navigate the levels and puzzles! I did have two issues though. The "error" reaction, when you scale into a wall, is a bit overly sensitive for my tastes. It can make something as simple as moving onto a ledge a bit tedious if you're not extra careful about where you're dragging your mouse. The other issue I had, though this is more subjective, is the zooming in feedback to let you know when you're scaling, while useful, can become tiring and a bit distracting. It goes well with the aesthetic, but I believe putting in an option to turn it off with an alternative feedback could be useful, and might make the game more accessible.
Regardless overall I really enjoyed it, it's a really cool concept, and I think you executed it excellently! :D