Chipping away at the walled garden.

Mobile carriers are no longer the only game in town for buying content for handsets. For years, adding games and other content to phones has meant going through carriers' "decks," which are the menus used to buy carrier-approved applications.

Now, US mobile games sold through carrier decks are predicted to generate 72% of revenue in 2012, down from 90% last year, according to Parks Associates' "The New Frontier: Portable and Mobile Gaming" report.

“Off-deck marketing and distribution, combined with new business models such as mobile game advertising, episodic content delivery, and micro-payments, will rekindle industry growth," said Yuanzhe (Michael) Cai, director of broadband and gaming at Parks Associates.

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