Back in February, we speculated that the city building genre was about to take off, a trend that seemed to culminate in Playdom’s hit Social City. But creating and running a town is a compelling mechanic that doesn’t appear to have run its course. The latest game from Playfish is evidence of that: My Empire, which transports players back in time to construct a Roman city.

Playfish didn’t go out of its way to announce My Empire; we had to hear about it from Social Game Central, and at the moment the game reports a piddling 140 monthly active users, many of whom are complaining about a persistent bug. So think of it as a soft launch, perhaps intended to test the game without competitors immediately getting a look at its features.

That’s probably a good idea, because My Empire takes a step beyond most Facebook games, in terms of complexity. As soon as a new player enters the game, a half-dozen new city management concepts pop up: population, fame, happiness, tax collection, and a variety of building resources.

We’ll get to most of those in a moment — but first, about the tax collection. This is a pretty brilliant idea, actually. Most time management games still involve endless clicking on crops and buildings. Playfish does away with the clicks by offering you a tax man who will gather taxes for a pre-determined period of time, at the end of which you collect the money with just one click. Time management still figures in, as you have to collect your taxes before “bandits” take them away.

Your taxes are partially based on population and some important buildings, but just collecting a bunch of money won’t get you through the game. First, to grow your city, you have to balance population and happiness. Houses must be built to attract new people, while most other structures provide happiness points that have to be balanced against population.

The concept is quite simple, but it’s more than we’ve seen from most Facebook games, even recently. The complexity notches up a few minutes into the game, when you’re suddenly notified that it’s time to build Stonehenge, which requires four resources like wood and stone.

Stonehenge? Rome? Well, it may be a bit apocryphal that your good Roman polis can eventually include structures like Stonehenge and the Sphinx, but Playfish obviously didn’t set out to give history lessons. But it is doing two clever things by combining Rome and Wonders of the World. The first is taking a page from Civilization’s book. Considering the enduring popularity of that game series, emulating any of its characteristics is probably a good idea.

The second advantage Playfish gets from its setting is Rome itself. Roman cities were extremely orderly places, by ancient standards, with a variety of civic structures and a well-defined bureaucracy, much like a modern city. By picking Rome, Playfish gets to avoid trying to replicate every modern structure — instead, it can add a bit of mystique while still putting us in a world with concepts we recognize.

Overall, the design of My Empire comes off pretty well, although I found myself playing on for longer than I would have expected. Most social games have a five minute introduction, after which you’re expected to go away for a while. Not My Empire, in which you start off with thousands of gold coins, while building new structures only costs one or two hundred coins.

The result is that you can actually build a pretty decent city on your first play, provided you’re willing to put in 20 or 30 minutes. The choice to give so many starting coins to players couldn’t have been accidental for Playfish; they’re obviously working toward longer playing times.

Another notable design choice is forcing players to invite friends to complete various structures, including a temple that will remain a blank spot on the ground until you find three friends. In the bottom right hand corner of the game, a small box also cycles your friends’ names and faces in a manner that makes it look, somewhat deceptively, as if they’re already playing. And, of course, the usual sharing and gifting buttons are all present.

It should be interesting to see where My Empire goes in the coming weeks. Our first impressions are of a well-designed title that takes cues from any number of successful PC games, including the Civilization, and Rome series and Zeus: Master of Olympus. But despite a growing number of deeper gaming experiences on Facebook, social gamers have yet to prove en masse that they’re interested in complexity.