Fun game, The art style is also fine, though I'm wondering whether it would look better to have folded corners on your book as buttons to switch pages instead of the arrows, but the arrows work fine anyway. The music is good, and the concept is interesting. Having a small button on screen for resetting to allow for the full mouse only experience would be nice, and like st4ng said, navigation with WASD or arrow keys would also be nice to have for those who want to use it.
It took me some time to realize, that the shadow was the indicator of things that could be duplicated, but the mechanic has another small problem which you may not have considered.
In the last stage, you can manipulate stuff with the machines, and none of them change anything about whether an element has a shadow or not. In my head I thought it was impossible to beat, because I expected the resulting gold from the final machine to NOT have a shadow like all ingredients I've put into them. But it did.
All in all, the most problematic thing with this game currently is the shadow mechanic, if you can make that one more clear, then the overall gameplay experience would be much smoother.
That said, the game has a solid foundation with its unique mechanics and charming presentation. With a few tweaks, it could easily go from a fun game to a fantastic one. I look forward to seeing how it evolves!
I see, this is interesting, I will take into consideration what you said to make consistent rules in the future about whether a resulting item has a shadow or not. Now that you're explaining this I understand the confusion.
Thanks you for this exhaustive review and for playing the game until the end, I'm glad you had fun despites these shortcomings :)