An overhaul to warfare in "Civilization V" takes conflict out of the cities and into the surrounding countryside.

‘‘Sid Meier’s Civilization” has always been gaming’s greatest strategy franchise. Its lessons in history and geopolitics, conditions for nonmilitary victories and ridiculous customizability give the series more replay value than anything else out there. Since my college roommate introduced me to the first “Civ” in the early 1990s, I’ve easily spent more time on the “Civ” games than on any other gaming franchise.

As in past “Civilization” games, “Civ V” (rated E10+, $50 on PC, requires online activation) puts you in charge of one settler and one primitive warrior. You’ll use that settler to found a city and from there create a military, expand your borders and research technologies, beginning with simple inventions like “animal husbandry” and extending all the way out to “nanotechnology.”

Along the way, you’ll run into other civilizations that you can conquer or collaborate with. There are several ways to win, ranging from conquering the whole world to colonizing another planet or currying enough diplomatic favor to take charge of the United Nations.

Though “Civ V” will feel familiar to longtime fans of the series, it sports a number of refinements and new features that weren’t found in 2005’s “Civilization IV.”

One of the first things you’ll notice are city states, isolated one-city governments throughout the world that aren’t competing to win the game. Incapable of founding second cities, these entities are meant to be a key driving force in shaping “Civilization V’s” narratives.

Each city state has its own influence meter. The more sway you have with a city state, the more benefits you’ll reap, from resources to the occasional gift of a military unit. But friendship does not come without costs. You’ll often be expected to pledge to keep your little buddies safe from other civilizations who try to bully them. Because city-states just consist of one settlement and a few military units, an aggressive, militaristic civilization can take one out pretty quickly, so you’ll need to be fairly watchful of your allies.

While you can go through the game treating the city states you meet as enemies to be conquered, the fact that each city state has several relationships with other world powers makes things more complex. If you, say, declare war on Oslo, you might have to contend with one or two other world powers who are allies or friends of the city in question. City states that are about to be wiped off the map will often appeal for aid from other world powers, which can help out by contributing money or military units.

Similarly, allied city states will jump in to assist larger civilizations they’ve allied with. When I declared war on the Romans, I was taken aback when Copenhagen and Ragusa, both neighbors of mine, jumped into the fray, forcing me to fight a three-front war.

The artificial intelligence in "Civilization V" occasionally leaves computer-controlled units vulnerable to ranged attacks.

Once you go to war, you’ll experience “Civ V’s” vastly superior combat system. Whereas past “Civ” games allowed you to stack dozens of units on top of one another and made every conquest a war of attrition, “Civ V” allows only one military unit per hex on the map. This means that, for the first time, combat comes out of the game’s cities and into the surrounding terrain. Part of building a good defense is recognizing and controlling chokepoints on the map, or catching enemy units off-guard with archers and cannons that can fire over distances.

The new combat system feels like a much-needed shakeup, but it’s a shame that it feels like your computer-controlled opponents haven’t mastered the rules of engagement. In the lone mixed review I’ve seen of the game, 1UP.com’s Tom Chick says that the longer you play, the more likely you are to become disheartened with stupid combat AI that frequently leaves key units unprotected or executes strategies that are just plain dumb.

I haven’t played enough to think this design is a game-killing flaw, but I’ve definitely seen a few head-scratching moves. Firaxis has already announced the first patch for the game will attempt to address some of these issues, as well as errors involving crashed games and corrupted saves. (I, thankfully, have had none of those problems.) If the patch doesn’t go far enough on the AI, it may have to be fixed by a savvy modder.

If you played a lot of “Civilization Revolution,” a streamlined game playable on Xbox 360, PlayStation 3, PC, iPad and iPhone, there’s a bit of an adjustment to make to “Civ V’s” much slower pace. This is a game that’s meant to unfold over a dozen hours, minimum. Though you can take a hands-off approach to development and avoid micromanaging your cities’ populations and workers, that’s not the key to an efficiently played game. “Civ V” will require even more of an adjustment for gamers who’ve only played “Civ Rev,” in which games can generally be wrapped up in a few hours.

In a new wrinkle for "Civilization V," leaders now speak in their native languages.

Despite some issues with artificial intelligence and the aforementioned stability problems experienced by some players, it’s hard to consider “Civ V” anything but a smashing success. Because new “Civilization” games come out, on average, every four or five years, this game will be reworked, remixed, expanded upon and modded until it’s a finely tuned classic that can be tailored to anyone’s play style.

The elimination of unit-stacking feels like a long-overdue, much-needed overhaul and totally changes the way “Civilization” plays. (And if you miss unit stacking, there’s a mod you can install to get it back, accessible through “Civ. V’s” first-of-its-kind, built-in hub for user-created mods.) Add to that the fact that “Civ. V” is the most visually lush, well-presented game in the franchise to date and you’ve got a title that’ll keep strategy nerds, PC gaming diehards and history buffs saying “one more turn” into the wee hours just as much as its predecessors.