Credit: De Lu/Feature China/Newscom

Angry Birds is maddeningly addictive.  People play the game for hours on end, hate themselves for doing it — and keep playing.  It is one of the most popular mobile apps in the history of mobile apps, and it has made millionaires of its makers at the Finnish company Rovio.

Now there’s a spin-off — a game at the Window of the World theme park in Changsha, China, though it was apparently started without Rovio’s approval.  Stories have been popping up all over the web, showing people using slingshots to shoot plush-toy birds at their targets.

A bit of background, if you’re one of the three people in the solar system who’s not been hooked: Angry Birds is a video game, best played on a mobile device (an iPhone, iPad, Android, etc.) with a touch screen, in which you shoot flightless birds at evil green pigs — who happen to be protected in weird structures of wood, ice or stone. There’s a devilish pleasure that comes from hitting them at just the right angle and watching them come crashing down as your point total goes up.

What do you do if you’re Rovio, and you were already trying to expand into China — and someone else capitalized on your idea? The company has not, so far, replied to messages from ABC News. It has already been selling Angry Bird plush toys; now stuffed birds are turning up on China Daily.

“This serves as a method for people to purge themselves and to gain happiness,” said an unnamed park official on a Chinese gaming website.