Can you believe two years have passed since we first heard of the game Angry Birds? Well this Sunday marks that day, a full two years of slinging, throwing, smashing and catapulting various birds into rotund egg thieving pigs. The makers of the game, Rovio, have enjoyed unprecedented success over the last couple of years with over 500 million global downloads and have rapidly become one of the fastest growing international companies of its time.

To celebrate this fine day the delightful team at Rovio has launched a “Happy Birdday” update available free to all its fans. The update will unlock 12 delicious birthday cake levels, which include special birthday achievements and new graphics and menu.

The fun doesn't stop there as Rovio has a multitude of special events too, where you can celebrate in person and be in with a chance of some fun giveaways. If you're in the UK head over to your local Forbidden Planet store on Sunday morning, where they will have a special Angry Birds section including lines of stock that have never been available in the UK – plush!

In the US fans can celebrate with Barnes & Noble, which is host special giveaways during 11am and 3pm on Sunday. The store has gone all out and is also holding an Birds & Noble Scavenger Hunt to find the Mighty Eagle, plus an Angry Birds raffle, high score contests, the chance to design new characters AND an Angry Bird parade – someone's a fan! Toys'R'us, not to be outdone, is also celebrating with 25% off all its Angry Birds plush toys and a free code that will unlock a secret bonus level in the Google Chrome version of the game.

If all that wasn't enough, Rovio has also released a new video, where we are told the pigs are up to their usual tricks...