Inside Social Games

Social sports applications are some of the oldest and most literally “social” games on Facebook: Users compete with friends to do things like create fantasy sports leagues or pick winners for tournaments like the March Madness college basketball championships happening now. These apps can also be a more powerful way for more traditional sports companies to reach Facebook users.

And so, Yahoo is buying Citizen Sports, one of the leading social sports developers on Facebook, for an undisclosed amount. In the announcement press release, Yahoo describes how the company will fit in with its destination site, Yahoo Sports:

Yahoo! Sports’ content will be integrated into [Citizen Sports' products], creating a seamless experience for sports fans wherever they are. On Yahoo! Sports, users will be able to broadcast their allegiances, create or join a conversation with friends and fans and cheer for their teams through Citizen Sports’ applications.

Citizen Sports currently has 719 applications (many for specific teams) on Facebook, according to our independent measurement service, AppData, for a total of 1.51 million monthly active users and 156,000 daily active users. It appears to have an early lead over rivals CBS and Watercooler, in terms of traffic to its March Madness bracket app. Yahoo Sports had 39 million monthly unique users in the US last month, according comScore — funneling these users into Citizen Sports’ apps will lead to more traffic on Facebook.

AllThingsD, which broke the story yesterday, reports that the startup raised $10 million from Kleiner Perkins Caufield & Byers partners Kevin Compton and Doug Mackenzie, through a separate investment vehicle, Radar Ventures. It used to be known as ProTrade, the virtual sports stock market, before it changed its name and product line and started building social apps a couple years ago.