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) Android in some nations. An update called "Bad Piggy Bank" enabled players to buy out the in-game ads. In October 2010, Microsoft suggested on one of its websites that a Windows Phone version of "Angry Birds" was in development. Rovio complained that Microsoft had not asked permission to make such a statement, noting that at that time it had not committed to design a Windows Phone version. Although Rovio asked Microsoft to revise its site to remove references to the game, a Windows Phone version was ultimately released in June 2011. Near the end of 2010, Rovio stated that it