The spectacular trajectory of the Angry Birds computer game, from obscure Finnish iPhone app to global ubiquity—there are board games, maybe even movies in the works—is probably inexplicable. Of course it's cheap and charming, but such catapulting success must owe a lot to serendipitous, word-of-mouth luck. Yet, prompted by my friend Trey Ratcliff, who created the gaming-camera app 100 Cameras in 1, I've been musing on whether there's an evolutionary aspect to its allure.

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