The game is moving, and fast. I applaud the devs.
However, I also think it is a good idea to be able to evaluate rules setting thouroughly.
I therefore suggest that certain parameters, such as city income increase rate, or say a tweak in unit cost, be exposed as game creation parameters (tweak a numeric value, select a checkbox, choose from a dropdown) instead of having global impact on everything.
Because while some may hate a rule change for the impact it has on say tank commander agression, it may be fun to have this rule active sometimes, sometimes not. And it would make the development / change cycle a bit more manageable for the devs, and give more power to the users.