Why stick with just one era of expansion and conquer when you could cover all of human history and then go far into the future as well? That's what's on tap if you decide to jump into Civilization, Sid Meier's 4X claim to fame.
As strategy games go, Civilization is the paradigm to beat. Its turn-based design has stood the test of time and influenced countless other titles. Games can play out as fairly quickly if you know what you're doing, and unique bouts abound no matter which of the hundreds of civilizations you pick.
One truly ludicrous example showcases a player who has been playing the same game of Civilization 2 for 10 solid years. No, not in-game years. Someone has spent a decade of their life on ONE Civilization match that never ended.