Arkadium is one of many casual game publishers making the shift to social games on Facebook, and it is adding staff to do so.

In the past quarter, the company has added 20 new employees to focus on social games and how to make money from them. The new employees will work on social game launches as well as Arkadium’s Social Connect platform, a new technology that will bring the company’s library of casual web site games to Facebook. The company also added a sales office in Los Angeles. Among the hires are Marten Engblom, director of engineering and formerly of He is leading the Arkadium Social Connect team. Another new hire is Coray Seifert, senior game designer, and a former THQ employee.

The company now has more than 100 employees at its headquarters in New York and Ukraine. The company’s first game on Facebook, Mahjongg Dimensions, has more than 1 million users. Overall, 6 million users a month play Arkadium games.

Since 2001, Arkadium has published more than 300 casual games that can be found on web sits of clients such as MSN, Hearst Magazines Digital Media, ESPN, ABC, Lifetime and Discovery. The self-funded company is run by Kenny Rosenblatt, chief executive, and his wife Jessica Rovello (both pictured), president. Rivals include PopCap Games, Oberon, Real Networks and Playdom.