Overall, 10 of the 14 Angry Birds games, including the spin-off Bad Piggies, ranked No. 1 in at least one of the following App Store categories: top free app, top paid app, top grossing app, top free game, top paid game, or top grossing game.

However, Angry Birds hasn’t been as successful on Android. The franchise’s biggest hits on the platform are: Angry Birds Star Wars II, twice ranked a No. 1 paid game on Google Play; Angry Birds Slingshot Stella, which held the top spot in the free games category for four days; and Angry Birds Epic RPG, which enjoyed two days as Android’s top free game.

Rovio can attribute much of its staying power to the timing of the original Angry Birds. In 2009, the App Store was “still an open field,” says Jeff Yates, Sensor Tower’s vice president of operations, and mobile games hadn’t yet reached the level of sophistication found in titles like Clash of Clans, which holds the record for most days (667) as the top grossing iOS app. (Angry Birds ranks third in that category, behind Candy Crush Saga.)

“The production quality, I think, can’t be understated,” Yates tells Quartz. “2-D physics at the time was starting to emerge, and they did a great job of it. … I think those things set them up for outstanding success.” Though he admired the mechanics and simplicity of the game at the time, he questions if people will be just as excited for a 15th Angry Birds title.

“If you look at the trajectory of the company and its strategy to do that singularly on the back of one property,” he says, “I think it played itself out.”

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