I remember seeing those advertisements for “one turn more” support group for people addicted to civilization. and the story of the novelist who had to delay publication because he played too much civilization.
Why is this game so addictive?
Well, for starters, turns tend to go by easily, which lends to the “just one more turn” effect.
I like how every game played is different and each AI has a distinct flavor. Sure, you can get victory with your usual method, but the path to that victory is always different.
I play Civilization a lot, and it’s because there’s always one more thing to do:
“If I play another few rounds, I’ll have democracy.”
“Just one more round, and I’ll take the Babylonian capital.”
“Damn them for taking Paris, and learning about space flight, but soon I’ll have nuclear weapons, and I can nuke Washington!”
Also, there tend to be a lot of multi-turn achievements that you’re building towards at any given time; by the time you’ve played those two more turns to get your next tech advance, you’re only a couple turns away from building that Wonder, and then you just need a few more turns to finish off the damn Aztecs, and so on.
There’s two senses of “addictive” here:
“…just…one…more…turn” - as mentioned, there’s always something about to happen, which keeps you glued to your seat
Replay value - as also mentioned, each game has the capacity to be wildly different. You have a wide range of strategies you can adopt; you play against a host of different characters all with their own strategies; new map types demand new approaches to expansion, tech discovery, military stance; there are vastly different ways to achieve victory. But above and beyond all those differences, *you *change as a result of playing Civ. You develop new strategies, which means you want to test them out. As you get better, the game gets harder to match you (although most people seem to innately dislike the handicapping in the harder levels). So there is always more to explore, and more to challenge you.
It’s not just that every turn, there’s something to do. It’s that every turn, there’s something on the horizon that’s taken forever to get to. If I were to make a computer game, I’d have rewards that take forever to earn, but are so numerous that you get one every other second. Then everyone would put my name in the title of their threads.
Right, when I’m on turn 38 out of 40 on a new tech (or a new wonder, or whatever), it feels like I’m almost there, almost at a stopping point, so I might as well play those last two turns.
Personally, the method I’ve found for keeping my play under control is to run iTunes in the background, and load up a playlist of about an hour’s worth of music (maybe two hours, if it’s a Saturday or a vacation). When the music stops, I finish the turn I’m on, and then quit, no matter what I’m getting on the next turn.
Ok, are there any other games that are similar to civilization 4 and just as good? Or is this one of a kind?
I recall Civilization II being rather addictive. 
It’s a totally different game, but is almost the same game, if that makes sense…
The Sims
Hours and hours and hours of my life spent on this game. I still only play the first Sims, but that has more than enough for me. I did spend some good hours on the Sims 2.
SimCity is an excellent game, with the same long term playability and variability, but it seems to have more of a lower boredom point.
EverQuest did this. World of Warcraft does this better than any game so far. That’s why millions of people stay up too late, that’s why people are willing to pay a small fee every month to play: there’s always something else just over that next hill!
Tetris.
Nothing else comes as close enough to scratch the historical warrior/politician in me. There are better games for specific things, but none that do all ages on such a large scope that is as accessible.
Man, no matter what improvements may have come in the gameplay, the wonder movies aren’t nearly as good as they were back then. They used to really match the accomplishment and grandeur of a wonder of the world. Now… eh.
(Though, to be honest, even though I own Civ IV, I’ve only just barely played it.)
Civilization IV gives me a chance to test my pet socioeconomic theories (at least within the world of the game). Right now, I’m convinced that if I ramp up production (hammers) sufficiently ahead of all other civs, it doesn’t matter if I’m throwing swordsmen against macemen, I’ll prevail in the end*. Hammers are the key to the universe. (Or not. Let me test that theory . . . )
(*I’ll concede this may be a dicier proposition once I begin throwing knights and macemen against planes and tanks)
ETA: Also, I’m sure that each continent has a choke point that gives me a strategic edge. Let me found my capital next to an isthmus and it’s all gravy . . . except when it’s not. Maybe I should focus on coastal areas instead? Or seize the center of a landmass? Let me see . …
People tend to love the EU games and the GalCiv games. I still like to play MOO2 and even MOO. There’s lots of old 4X games out there, some of which are definitely better than others.
I have loved Civ games since the first one. I just played a loong session of Civ IV the other night. Just one more turn, indeed.
I tried the demo of Civilization Revolution on my iTouch, it’s very good. Simplified in some ways but richer in others. I’ll probably buy it.
Truly, the Civ games are the best games of all history.
But then again, how many games of all history are there?
I don’t find it adictive at all. Gotta go I’m attacking Rome 
I still play.