Thanks for such comprehensive and complete feedback.
Agree with all your points, they all were considered and not done only due to time constraints. If we pursue to continue this game forward we will implement all of this.
We also planned on having 3 more stations and more mechanics, but unfortunately that was too much.
As for percentages, its on base number and not current one, so if we go from 10 and do multiple upgrades that each add 70%, those percentages add up additively instead of multiplacatively and final value increases not that much. We have seen its done this way in multiple games so decided to keep it.