"Facebook rocketed to prominence as a gaming platform in 2009 and 2010," said Steve Bailey, senior analyst for games at IHS. "However, with equal speed, the market then settled into a state of maturity in 2011, with conditions becoming markedly more challenging for game operators. While Facebook remains a worthwhile opportunity for companies able to meet these challenges, the tone of the market in 2012 will be somewhat muted compared to the optimistic outlook of the past few years."

The cost for companies to acquire new users has grown to a staggeringly high level. After Facebook cracked down on games spamming news feeds, most companies all but lost the ability to reach new players via word of mouth. That means transitioning to more traditional, more expensive and less effective forms of advertising. And growing player expectations is also driving up cost.