400 Turns Of Civilization V. You should try out CCV for Civ 4.
Simply named "Community Civilization 5," it is a community project that sought to bring features the community wanted in Civ 5. This includes features like Barbarian states eventually emerging as city-states, revolutions being able to take place within empires to form rebel states, and a slew of new units, promotions, technologies, and buildings. This includes a Future Era (mechs, etc.), some Cold War aspects with espionage (pre-targeting nukes to enemy cities now influences whether or not they will declare war on you, i.e. the bomber gap, the missile gap), and so much more. Nexon Games. Combat Arms. Vindictus.