Ben Vu wants his Battle Bears mobile game to become a big entertainment brand. So it isn’t so surprising that the chief executive of SkyVu Entertainment has set up some big billboards all over San Francisco touting the characters.

The mobile game franchise isn’t necessarily a household name yet, but the game series has surpassed 20 million downloads, and Battle Bears Royale launched on the Google Play store today. It’s a cross-platform multiplayer shooter title that’s also available on Apple’s iTunes App Store.

The billboards have led to a nick uptick in downloads, said Vu. And yes, those bears are farting rainbows at the Nugz birds. (The city of San Francisco did not approve of the rainbow farting, so SkyVu strapped a pot-o-gold to Huggable’s back instead.

Omaha, Neb.-based SkyVu previously raised a round of venture funding for its brand expansion. I guess we know where that money is going.

The company has become famous over the past four years for its Battle Bears games. The series of tough-talking cute bears — great for young boys stealing time on their parents’ iPhones — has enabled SkyVu to rise up from the sea of iPhone game developers, graduating from garage startup to a real business with dozens of employees and millions of dollars in annual revenue. The funding fits with the trend of the year, in which a third of all new funding for game companies is going into mobile game startups, according to investment bank Digi-Capital.

Vu was previously an animator in Hollywood, working on films such as Coraline. He started SkyVu in 2009, hoping to create games with animated characters that would resonate with fans. Battle Bears was an instant hit when it debuted in August 2009 as a paid iOS game. It made a critical transition to free to play last year, allowing users to play for free and pay real money for virtual goods. The game is distinct in that the studio creates its own full cartoon animations in between levels. The average time spent in the game is 15.5 minutes per session, more than the typical iOS title. And monetization is three times as high as the average revenue per paying user.

Now, Vu is excited about taking game characters and transferring them into other media such as films. The potential for that kind of “transmedia” property with Battle Bears is one reason why the company was able to raise money.