I did a little research on what I assume are the top 3 OSG’s (in terms of traffic): Evony, Travian, and Ikariam. Granted this isn’t a great analysis, as I only looked up the .com’s, so this doesn’t take into account Travian and Ikariam’s .de servers or the other domains they have around the world.
Nevertheless, it’s probably a close-account of where these games stand. I found the breakdown of the percent of site traffic by country especially interesting. Over 75% of Evony users are from English-speaking countries, and who knew Ikariam was so popular in Saudi Arabia?