Angry Birds (video game) was being played, the staff liked the characters, and the team elected to design a game around them. In early 2009, physics games, such as "Crush the Castle", were popular flash-based web games, so the Rovio team was inspired by these games. During the development of "Angry Birds", the staff realized the birds needed an enemy. At the time, the "swine flu" epidemic was in the news, so the staff made the birds' enemies pigs. Angry Birds was the studio's 52nd produced game and on its initial release, the game did not sell many copies. After Angry Birds was a
Angry Birds (video game) in "Angry Birds Rio" and the introduction of 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