That sounds so great! Can not wait for further development :)
Most likely I will preorder it as soon as possible
As a suggestion, you could use kingdom wide laws which buffs and debuffs as a new mechanic. Build a court house and with different kingom tieres you unlook different law slots. Eg: Draft - maintenance of troops go down, happyness of the population goes down; subsidies for farmes - you lose gold every month, but farms get a production boost; taxes could also be part of this or a singular building, named treasury :)
Just an suggestion but I´am interested in your opinion