Well, first of all, game idea is same from 1-4 if you've played any of them.

I dont want to bore you with super long explanation. wait I know......turn-based strategy game that challenges players to build and expand an empire, throughout all of human history, and become the most powerful ruler in the world. Choose one of 18 nations to lead and go head to head with some of the most famous leaders in history. Each civilization has its own special characteristics - some are fairly peaceful, while others are expansionists and conquerors. However, Civilization IV is more than just a great combat game: you can also achieve victory through diplomatic cunning, cultural or religious alliances, and technological dominance.

start as cave man, cant see the globe, research shit and spread religions, get satelites, then start nuking fuckers.

fairly complicated strategy/turn based combat. Lots of trading and alliance shit. you can make a game so that it will last for 2 - 40 hours. Played for 3 last night.