Angry Birds, a hit game by Rovio, a small Finnish company, is one of the unlikeliest pop-culture crazes of the year — and perhaps the first to make the leap from cellphone screens to the mainstream.

Angry Birds, in which the birds seek revenge on the egg-stealing pigs, is meant to be easily played in the checkout line and during other short windows of downtime — but some players have trouble stopping. Rovio says people around the world rack up 200 million minutes of game play each day. (Put another way, that is 16 human-years of bird-throwing every hour.)…

Rovio made a smart choice in making the birds angry, said Jesse Schell, a professor at Carnegie Mellon who studies game design and entertainment technology. “You can smash them into things and it’s O.K.,” he said. “Imagine if they were cute little birds. It might be kind of funny on some level, but most people would probably be a little repulsed.”