Rovio's very popular Angry Birds will turn two years old on December 11, and the firm is celebrating with a Happy Birthday update which unlocks all episodes and adds an extra 15 levels.
It will also include new menus, achievements and graphics.
Various retailers will also be celebrating, with US chains Barnes & Noble hosting special events and giveaways on Sunday, December 11 from 11am and 3pm, and Toys 'R' Us offering Angry Birds merchandise at 25% off, along with a code unlocking a special level in Angry Birds Chrome.
In London, Forbidden Planet will be celebrating, and in Japan, Rovio CMO Peter Vesterbacka will be holding a presentation at the Apple Store in Ginza. A special event will also take place in Tokyo's Harajuku.
Angry Birds has been downloaded 500 million times in its two years on the market.