Angry Birds is the world's most downloaded game and Wal-Mart is the world's biggest retailer. Now, they've come together, for mutual interests.

Rovio, the Finnish makers of Angry Birds have struck a deal with Wal-Mart. A new version of the game called 'Golden Eggsteroid' will be made available only in Wal-Mart starting March 22. So how will this work? It's more than the mere exclusivity of selling the new Angry Birds game in the store.

Anyone who's played Angry Birds knows only too well the importance and excitement of "unlock". So, the deal is that only Walmart customers will have access to the clues of 'Golden Eggsteroid' which will unlock four bonus levels.

The first four special clues can be collected by going to Wal-Mart's facebook page. The other clues, however, are not so easy to get. For that, there's a bit of treasure hunt to be played and here's where the mercenary part kicks in. The remaining clues for unlocking the levels are planted in the exclusive and limited-edition merchandise sold in Wal-Mart stores. These include clothes, toys, mobile phones and even food items. Golden Eggsteroids could be hidden anywhere - on the price tags, on the snack boxes, or on the design itself.

The two companies are claiming that this is being done for "fun" and for providing Angry Birds fans with a "unique experience". Unique is right, but is it dragging through the doors of Wal-Mart, and buying merchandise to look for clues fun? Ask the die hard Angry Birds fans who love their couch and their smart-phones and iPads.