I do not like the graphic in Civ4 as much as in Civ3, but the rules and AI is a lot better than in Civ3. Does anyone thought of replacing the new graphic with the old one ??? I mean this game has always been a really good strategy and the new graphics makes it worse in a sense that it lost its cool atmosphere. It is more childsih, more colorful ... This game was not about it. It was more about options to choose, difficulty, complexity etc. What do you think ?The rules and the AI, just as I said is much greater !!! It's a matter of graphics ...

well, the problem is that civ3 is 2D and civ4 is 3D.

the easiest thing would be the terrain-textures. but it would just be the textures, the terrain itself would remain 3D.

as for the cities and units it would be much more complicate. there you have to do either complete new models that looks like the ones in civ3 (a hell of work) or you just replaced them with flat 3D-objects and *paint* the textures of the untis and cities on it. but this way the units don't have animations.
and it would still be in 3D.

this way i think it's much more easier to do a civ1-graphics-mod for civ4 (civ1 terrain-textures has already someone done i think) than a civ3-one. since you just need flat 3D-objects, that lies on the terrain and put the textures of the units and cities on it and finaly to go into *top-down-view aka satelite-view (alt+f)*.
but it's also still 3D :)