'Angry Birds' aims for 1 billion fans

(CNN) -- Just how big is mobile game phenomenon "Angry Birds"?
Players have slingshotted more than 100 billion virtual birds in the game's many versions, more birds than actually exist on the planet.
That's according to Peter Vesterbacka, chief of Rovio, the Finnish developer behind the blockbuster game. Speaking on a panel Thursday at Fortune's Brainstorm Tech conference, Vesterbacka said the game has surpassed 300 million downloads and has set its sights on becoming the first entertainment franchise with 1 billion fans worldwide.
To reach that goal, the game's makers are expanding way beyond their pig-pulverizing core product, which has been a top app for iPhones, iPads and Android devices for more than a year. "Angry Birds" toys and stuffed birds have been hot sellers, and a board game hit stores this spring.
Also in the works are an animated series, a possible feature film and even a series of books, including a cookbook of egg recipes.
"We've been told time after time that we're not supposed to do movies, TV and toys," said Vesterbacka, wearing his now-trademark red sweatshirt with an "Angry Birds" design on the front. "We've sold something like 8 million toys. If you have a strong brand, you can do anything."
Players of "Angry Birds" seek to advance to new levels of the game by sending birds crashing into fortresses built by their nemeses: pigs who have stolen the birds' eggs.
In designing the game, Rovio's developers tried to strike a balance between challenging players and frustrating them with levels that were too difficult.
"It's really important that we don't punish the player," Vesterbacka said. "There's a great sense of accomplishment when you finally clear that level you've been stuck on for days."
Games like "Angry Birds" should be addictive, but not in an unhealthy way, Vesterbacka said. "It shouldn't be like smoking."
Panelists Thursday agreed it's hard to predict when a video game will catch on with the public. But Vesterbacka said people shouldn't just chalk the success of "Angry Birds" up to luck.
"Angry Birds" was built to be a hit. We were very analytical about it," he said. "We built 51 games before 'Angry Birds,' so it wasn't an overnight success."