Conquering the world is addictive.
4X turn-based strategy game is a major obsession of mine. It's probably good that I don't have a good way to count up the number of hours spent on such games, since Civilization V alone is up over 200 hours according to Steam. I played both the original Civilization and Civilization IV a whole lot more than Civilization V, so I'm sure I'm easily into a four-digit hour count on the Civilization series alone. Add in all the other 4X games and it might end up being a five-digit count.
That's not to say that I'm particularly good at 4X games. Most of them have 3-5 difficulty settings, and I can usually do well on the middle setting. I might try the occasional game on a higher difficulty, but those tend not to end well. I like the big, sweeping strategy aspect of these games, but the higher difficulties seem to require a lot of micro-management. I don't have the temperament to stay focused on every detail for hours on end.
Civilization is the big name in the genre, but I've played a whole lot of other 4X games. My all-time favorite is still Master of Magic, which is set in a fantasy world (or two worlds, depending on how you look at it). That game is more than twenty years old, and I still fire it up every once in a while to cast the Spell of Mastery. Then there's the galaxy-spanning space games like Master of Orion. The world you conquer can be as large or as small as you like.
Part of the appeal of these games is that there are so many different ways to play. Nearly every 4X game gives you the option of different permanent bonuses, usually tied to a race or character that you choose at the beginning. Games play out very differently depending on which bonus you have. The same goes for choices made throughout the game, particularly technology research. If you're trying to win a military victory, better have your scientists focusing on weapon technology, or you might end up sending spear-waving warriors into a hail of rifle bullets.
Firing up one of these games is a good way to lose several hours at a time. Each time you finish moving all your units, setting your production, directing research, and so on, you naturally want to see how it all turns out. So you end the turn, and inevitably something didn't go quite according to plan, or simply needs a bit more time. So you make adjustments, and take another turn. And another. And another. Then you look up, and it's four hours later.
The next big 4X release on the horizon is Civilization VI, due out sometime in the fall of 2016. I tend to be about a year behind the curve on these releases, largely because I'm cheap and don't like paying full price, but also because there are inevitably bug fixes and balance adjustment patches. Some of the additional content for Civilization V (i.e. Gods and Kings) added features that made it almost an entirely different game. So I'm likely to wait a bit on the newest installment in the franchise, at least until it hits its first Steam sale.
In the meantime, 4X game options abound. Maybe it's time to install Civilization V again. I hear there's a community patch that fixes a lot of the more annoying balance issues. Or there's Fallen Enchantress, or Warlock 2, or Age of Wonders III, or Endless Space, or another half-dozen games still sitting on my Steam wishlist. There's no lack of worlds to conquer.