Really interesting! My best score was 49K in 325 days.
I agree with @daria2b, I had the same kind of experience at some point. I wonder if it could be solved with some kind of feedback, like how close you are to starting to lose some satisfaction?
Anyway, it's true that you might have to spend some time re-balancing the mechanics. But good job at making this prototype!
I liked the visual experience with packing all these buildings in a small area, and I enjoyed trying to figure out the game mechanics and find out the best strategy.
The tutorial is a nice touch too!