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) birds higher and faster. Power-ups can be purchased in-game or given by friends who also play the game. "Surf and Turf" would later be included in the original mobile versions of the game, starting with iOS. The Facebook version features weekly tournaments among your friends, with the top 3 winners earning free in-game "Bird Coins" which can be used to purchase power-ups. There was a unique Green Day themed chapter, however it was removed in December 2012. At the 2012 Electronic Entertainment Expo in Los Angeles, California, Rovio and distribution partner Activision announced plans to bring "Angry Birds" and two