Re

Release

The initial iOS version of the game included a single episode entitled "Poached Eggs", which contained three themed chapters, each with 21 levels. From time to time, Rovio has released free upgrades that include additional content, such as new levels, new in-game objects and even new birds. As updates have been released, they have been incorporated into the game's full version offered for download from each platform's application store.
The first update, released in February 2010, added a new episode called "Mighty Hoax", containing two new chapters with 21 levels each. Updates released in April 2010 added the "Golden Eggs" feature, which placed hidden golden eggs throughout the game that would unlock bonus content when found, and a new episode called "Danger Above", which initially contained a single chapter of 15 levels. Two later updates added two more chapters to "Danger Above", each with 15 levels. "The Big Setup" episode, released in June 2010, added a new chapter with 15 levels and additional Golden Egg levels.^[22] "The Big Setup" was later given two more chapters of 15 levels each.
A fifth episode, called "Ham 'Em High", launched in December 2010, in celebration of the game's first year in the iOS App Store. "Ham 'Em High" contained 15 Wild West-themed levels in a single chapter;^[24] updates in February 2011 and March 2011 each added one new 15-level chapter.^[25][26] "Ham 'Em High" also introduced the Mighty Eagle, a new bird that may be used once per hour to clear any uncompleted levels.^[24] The Mighty Eagle can also be used in previously completed levels, without the once-per-hour limit, to play a mini-game called "Total Destruction" in which the player attempts to destroy as much of the scenery as possible, both with the standard birds and the Mighty Eagle; achieving 100% destruction earns the player a Mighty Eagle feather for the level.^[24]
The Mighty Eagle is offered as a one-time, in-game purchase,^[21] and was initially only available for iOS, as its App Store customers have iTunes accounts with pre-linked credit cards.^[27] In late 2011, Rovio also added the Mighty Eagle to the Chrome App version of the game. Rovio has begun testing an Android update called the "Bad Piggy Bank" with the Elisa wireless service in Finland and T-Mobile, which allows users to charge in-app purchases, such as the Mighty Eagle, to their mobile phone bills. ^[27] The service went live on Android with the release of version 2.2.0 in August 2012, using Google Play's transaction system, which allows both mobile billing and credit cards, allowing both Android phones and WiFi-only tablets to unlock the features. This version also added the powerups from the Facebook version and added an option to pay to remove ads, allowing Android players to enjoy the game ad-free as iOS players do.
The sixth episode, "Mine and Dine", was released on June 16, 2011 with 15 new mining-themed levels and a new Golden Egg.^[28] An August 2011 update expanded "Mine and Dine" with two more 15-level chapters.^[29]
The seventh update, "Birdday Party", was released on December 11, 2011 to commemorate the second anniversary of the first release of the iOS version into the iTunes App Store.^[30] It included 15 new birthday cake-theme levels, as well as updated graphics and the addition of elements from the spin-off games, such as the scoring graphic seen in Angry Birds Rio and the introduction of the orange bird that first appeared in Angry Bird Seasons.^[31] The update was later released for Android and Microsoft Windows. The eighth update was released initially to iOS on March 20, 2012 in a lead-up to the release of Angry Birds Space. The new update included an animated tutorial, enhanced gameplay, all new UI graphics, and the first 15 levels of "Surf and Turf," the Angry Birds Facebook-exclusive episode (see below); another 15 levels were added later, with the iOS version receiving the power-ups first seen in the Facebook version.^[32][33]
In August of 2012, Rovio announced a partnership with the punk band Green Day which will lead to 10 new levels of Angry Birds featuring all three members of the band. The new levels will showcase each member of Green Day as a green, bad pig and will also feature Green Day's latest single, and an exclusive track