I don't know much about modding so this is probably impossible/massively impracticable to implement, but have you considered having multiple difficulty sliders?
One game which did this was the nameless mod for Deus Ex, where as well as having the normal easy, medium and hard settings it had a custom option where the player could change the amount of bad-guys that appeared, how much ammo could be found and of course how much health bad-guys had.
Again I don't know much about Civ4 modding, but would it be possible to have different difficulty settings for the economy and such?
Say on the higher settings more buildings gain the -gold effect, but on the lower settings walls lose their -gold effect or something.
One game which did this was the nameless mod for Deus Ex, where as well as having the normal easy, medium and hard settings it had a custom option where the player could change the amount of bad-guys that appeared, how much ammo could be found and of course how much health bad-guys had.
Again I don't know much about Civ4 modding, but would it be possible to have different difficulty settings for the economy and such?
Say on the higher settings more buildings gain the -gold effect, but on the lower settings walls lose their -gold effect or something.