I was playing around with an idea of having a city that consists of mostly lumber mines. The reason being that lumber sells for much more than iron or stone, and a hell of alot more than food.
Heres what i had in mind;
50% of total mines are lumber, 25% food and 12.5% stone and iron.
This would make your city produce 4 times the amount of lumber than either iron or stone and twice as much as food.
The reason is more money income due to selling big amounts of lumber. Fair enough you have to buy iron and stone and most likely food too but youll still most likely make money even after that.
The only downside is the capacity of resources your city can hold for you. Mines hold a certain amount of resources for you along with warehouses and i am unsure yet as to how many warehouses you would need to be able to hold the maximum amount of resources needed for the most expensive building, which i belive are level 10 walls but i may be wrong.
Like i say ive just really thought this up a few days ago and thought i should put it in writing for critique.
Feedback would be nice.