FarmVille killer? Social City tops 5 million players in two weeks

City building games are the new hotness when it comes to Facebook gaming. Need proof? Playdom's Social City has exploded almost overnight -- topping 5 million players in two weeks, according to AppData.

The game plays like a snack-sized version of the classic PC game SimCity. The goal is to turn the city into a thriving metropolis by making money and increasing the population.

Specific activities include clicking on living spaces after a certain period of time (seven minutes and up) to keep them producing more population. Factories -- the money makers in the game -- must be assigned specific contracts, which can take from five minutes to two days to complete. Once the jobs are done, click on factory to collect the earnings and then assign more contracts to keep a steady flow of cash coming in. Money earned in the game can be used to expand the city limits and erect more buildings, and the cycle continues indefinitely.