Facebook currently represents only about a third of worldwide traffic for social networks, according to a recent white paper released by social games and apps platform Viximo and Superdata Research. The non-Facebook category of social gaming will represent the bulk of worldwide revenue generated in the social gaming market, the study states.

Further, the study found that non-Facebook platforms in Western markets will be responsible for nearly one-quarter of worldwide social gaming revenue within the next three years and that the majority of social gaming revenue is made on other platforms, beyond the borders of North America, where Facebook is the clear market leader.

These recent findings as well as strongly increasing user acquisition costs on Facebook are reason enough for us to examine international social networks that might offer opportunities to social game developers. In the first part of our weekly series we present the key facts on the German VZ Networks, which consist of StudiVZ, MeinVZ and SchülerVZ.