I agree that Civ 4 didn't really take the game to new heights the way 2 and 3 did, but it is probably the most sound and deep iteration of the series. It fixed all of the problems with degenerate gameplay that plagued the previous games and balances the viability of all the victory conditions. The tech tree and wonders are well tuned to make a lot of interesting strategies workable. The BTS expansion has the best vanilla AI in the series too.
On top of all that, it's the most moddable game in the series! I might just go see what people have done with it in the past couple of years... oh no...
On top of all that, it's the most moddable game in the series! I might just go see what people have done with it in the past couple of years... oh no...