A very good idle game! I love how you use only the pre-made assets and are able to craft a game with such a good atmosphere. The lightning is fantastic, too.
I have a few suggestions for the game too, just a few minor details:
1. For me, it can be a bit boring in the middle, before I unlock the crystal efficiency. Because the next level up isn't visible, it can feel like I'm not progressing at all.
2. The music doesn't continue after it has finished.
3. At the start, i'm quite confused on what to do, maybe add an in-game tutorial? (A simple mouse hovering toward it will be fine.) [I'm not the type to read the description unless neccessary, I want to experience the game as a whole.]
That's all! Pretty solid game nonetheless. 7.5/10!