A very competent game in terms of gameplay design. You can make different approaches out of small parts. And the fact that the level stays on the screen is also useful as it allows you to play with new tools. The project as MVP does very well, bugs do not break the game. And allows you to pass though and with problems, but completely to the end. I would like to give useful advice, but so that- to touch little obvious things:
For the future: Lacking the general impact, from the feeling of the action, you need to give the user hints.
* Muscles, lacks a hint of their radius. For the two connections.
* The wheel lacks a sense of speed, for this you can play with the shape (Size, Shift).
* Yo-yo (Which is looking down), lacks some discreet animation (bounce scale by Y) when the wheel finishes moving to emphasize that the bottom element has received the impact of stopping.
For the codebase, there's not much I can tell you without sources.
A very good game that brought good emotions. I recommend it