The ranks of casual gamers continues to grow at a rapid rate, with the number of people playing videogames in the U.S. rising 141% since 2008.

According to a new study by market research firm Parks Associates, 135 million people play a videogame at least one hour per month compared to 56 million four years ago.

While that’s a positive sign for the $16 billion a year games industry, there’s a catch: 80% of gamers prefer free titles like “Angry Birds” and “FarmVille” available on sites like Facebook and other platforms, opting to avoid subscription fees and pay only for add-ons and upgrades.

Still, they’re spending on average $21 a month on virtual goods or other perks, Parks Associates said, which added that occasional gamers with videogame consoles spend up to $27 per month.

Hasbro is looking to take advantage of those digital dollars by pairing up with social gaming giant Zynga to turn its toys into mobile games.

Deal, announced Thursday, also encompasses co-branded merchandising that will intermingle Hasbro and Zynga brands. First products should be available in the fall.

“It’s exciting to partner with Hasbro as we share a common vision for play and a mission to connect the world through games,” said Mark Pincus, founder, CEO and chief product officer of Zynga.

As a result of the move to play more games online, publishers are focusing more attention on building online communities for their top titles to entice players to open their wallets for more content, similar to “Call of Duty Elite” that Activision Blizzard launched around its “Call of Duty” franchise.

“Instead of ending support of customers after they buy individual game titles, game companies now focus on building gamer communities and developing ongoing relationships with their customers,” said Parks research analyst and study author Pietro Macchiarella. “The positive effect of this approach is that game monetization can be extended beyond the point of sale. Unlike traditional offline games, the online world allows the industry to earn revenue even when people play the same game repeatedly.”

In its most recent quarterly report, Activision, industry’s largest vidgame publisher, generated 26% of its sales from digital platforms, while 60% came from traditional channels.

With more people carrying smartphones, 17% of all consumers downloaded a game on their mobile devices, up from 7% in 2008.