This game turned me into the machine :D Nice twist. Thank you.
The hint for puzzle 5 may be more revealing - "you can connect the red combination nodes". Or something like that.
I think this would be very useful for children to learn. If you do decide to target children as an audience then tuning the game for mobile devices is important. I tried the game on mobile and the touch controls work. However not surprisingly, the point of dragging is way too small. You can make it larger because right now it is hard to point to it even with a mouse and a finger it's annoying. Good luck!