In yet another sign of the power of social networking, casino gaming systems maker IGT agreed on Thursday to purchase Facebook casino videogame startup Double Down Interactive for a potential consideration of up to $500m. The Double Down deal highlights the growing importance of social networking websites to traditional gaming companies, as Double Down enables IGT to reach millions more players online in a single day than the company could ever hope to in the smoke-filled parlors of Las Vegas or Atlantic City. But in a nod to the risk associated with entering a new market, IGT has hedged its bet by structuring the deal to include a $165m earnout (as well as $85m in retention incentives), which is equal to two-thirds of Double Down’s $250m price tag.

The transaction is one of the largest in the social gaming industry, and follows half a year after Electronic Arts made a similar move in buying PopCap Games for $750m (that acquisition also included a substantial earnout payment of up to $550m, or nearly three-quarters of PopCap’s deal value). Founded in 2009, Seattle-based Double Down’s large user base and rapid growth could help to explain why the company commanded such a large valuation for its sector. In November 2011 alone, its games received 54 million visitors, of which 1.2 million returned to play on a daily basis. Double Down also has a healthy base of what it calls monthly ‘active users,’ which the company said rocketed 30% from 3.3 million in October 2011 to 4.7 million at the time of acquisition.