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. An August 24, 2011 update expanded "Mine and Dine" with two more 15-level chapters. 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. It included 15 new birthday cake-themed 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 "Bubbles", the Orange Bird that first appeared in Angry Birds Seasons. 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. On October 9, 2012, the final chapter of "Surf and Turf" was released. Along with that, a new episode called "Bad Piggies" was released. This is to advertise the new Rovio game, Bad Piggies. Another update was released on December 11, 2012, the 3rd anniversary of the game's release, with 15 new levels to "Birdday Party" and 15 new levels to "Bad Piggies". The second set of 15 levels in "Birdday Party" introduced "Stella", the Pink Bird to the game. 15 more levels were later released for the "Bad Piggies" episode on March 7, 2013. On the same day these final 15 levels were released, Angry Birds became "Free App of the Week" on the Apple App Store until March 14, 2013 and became an instant hit on the Top Free App charts on the App Store until March 18, 2013, when the app returned to the normal price of $0.99. On June 17, 2013, Rovio teased on its Facebook page that Red, the main protagonist of the game, would receive an ability in a new episode. On June 26, 2013, Rovio released a YouTube video, uncovering three new facts: the episode would be called Red's Mighty Feathers, the