The flat tool is a joke if you try to build a city on a mountain map.
It is understandable that building on steep slopes is not being done nowhere in the world, however i think buildings should have a small foundation which should help even the plane although the field is not flat.
After playing a whole campaign on such a map it is painful and so tedious that it kind of takes the fun away.
I know there are more pressing things you work on but this with be a nice update in the future