Last year 2K games decided to take on a remarkable challenge; re-inventing a massive nation-building simulation that could be played over days, week and years into a quick-play, one-sitting home console experience.While Civilization purists may have balked at the results, there's no denying that Civilization Revolution opened up the strategy series to a completely different brand of gamers.Now, a year later, 2K is re-inventing the experience again for the iPhone.

Starting with one lonely settler, you'll set out to build the greatest civilization in the history of man.Building settlements, researching technologies, making monuments and developing culture — it's all here in the world of Civilization.If you've somehow never experienced the franchise before, consider yourself in luck; Civilization Revolution prides itself on being the most accessible game in the series to date.

The biggest changes seen to the Civilization formula in earlier releases of Revolution have all made their way here.Winning by a number of peaceful methods is still present but you'll find the neighbors in Revolution to be a little more demanding and war-hungry.  Barbarian villages and other artifacts are far more plentiful than we've seen in the past, allowing you to build up your bank/tech/arsenal with much greater speed.

Certain elements of the Civilization series simply didn't make the cut.A city view that allowed for a pride-filled (but completely unnecessary) view of the buildings you've constructed is absent from this edition.Trade and transit concerns have been severely stripped down.The technology tree has shrunken considerably.But for veterans of previous versions of Revolution, none of this will come as a surprise.Many of the changes you'll notice come not from a move to the iPhone but a move to this quick-play mentality.

Not everything that veteran players know and love has been removed here in Revolution.Much to our surprise Scenario Mode made the cut in the portable version.Scenarios allow you to play a game with pre-determined conditions, like engaging in a large sea-battle with a pre-existing civilization or fending off a Barbarian invasion.While none of these scenarios attempt to offer up the historical accuracy that we've seen in other versions of Civilization, they add a great level of challenge for seasoned players looking to hone their skills on the go.

While the changes made to the series make this an excellent build for the iPhone, there are a few small quibbles that hamper an otherwise excellent experience.Movement seems to be limited to the area visible on the screen, which means the days of dragging a warrior to the farthest point in the map and letting him explore on his own for a dozen turns is over.Zooming in and out of the map allows you to move him further, but once you get to the best distance you lose the ability to interact with your troops.This is by no means a fun-stopper, but still — small hiccups aren't without their frustration.

Gamers looking for that true, deep, seemingly endless Civilization experience may find themselves disappointed here.But if that's what you're looking for, chances are you're missing the point.Civilization Revolution, as a series, was designed from the ground-up to provide a simple, accessible, fast-session format of an old classic, and even here in the iPhone version it's done just that.Like The Sims 3 before it, Civilization Revolution joins that exclusive group of iPhone games that are just as good as the full version they're ported from.$9.99 is a steep price for any iPhone game, but if you're a fan of Civilization and have an open mind, you're going to find that this is $10 well spent.