Well polished factory game. The biggest hurdle I had was understanding the first level. The glass pane and glass bowl on the input node and constructor are barely visible, leaving me confused as to what the game wanted me to do.
As for the much requested leaderboards, check out LootLocker. I used it in a couple of my games and it's easy to set up (and free as long as you stay under 1000 unique monthlky users).
Great job !