Finnish game developer Rovio, which shot to pop culture stardom with the mobile game Angry Birds, launched Thursday a space-age sequel developed with the help of NASA.

"We've been working with NASA for quite a while already and they're very keen in cooperating with us. We got this astronaut Don Pettit in space to cooperate around the launch ... They've been helping us with all the physics-related questions around space and gravity," Rovio senior account manager Tiina Mikkonen told AFP at the launch in a Helsinki shopping mall.

The original Angry Birds game involved using slingshots to launch little birds at fortresses built by green pigs -- an absurdist, addictive game that quickly became the most successful mobile game in history, and which spawned an entire franchise of merchandise and media tie-ins.

The new game is based on the same premise, but places the battlefield in space, with the trajectory of the launched birds altered by the gravity of nearby planets.

In a viral YouTube video produced by Rovio, US astronaut Pettit used an Angry Birds stuffed toy and a green balloon to demonstrate the physics of the game in space.

Rovio held launch events in Helsinki, Seattle, and China on Thursday.

In Helsinki, the event was set up in a shopping mall, where passers-by were encouraged to try to hit a high score for a chance to win Rovio and Samsung merchandise.

"We are Angry Birds freaks. We've been waiting for this for a few weeks already," said Ville Markkanen, speaking on behalf of himself and his two-year-old son Arto.

Feedback from the crowd was positive, although 32-year-old Pauliina Ilvespakka said this game would be tougher for her toddlers to play than the original version.

"The kids are playing for maybe half an hour a day, unfortunately," she said, and admitted they were better at the game than she was.

Mikkonen said Rovio had put all of its eggs in one basket with Angry Birds Space, noting this was the only major game launch to be expected from the company this year, with more merchandise, tie-ins, and animated cartoons on the way.

Since its release in December 2009, Angry Birds has been downloaded 700 million times, and it is expected to exceed one billion downloads.