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) team settled on a minimum set of requirements, even though that left nearly 30 types of Android phones unable to run the game, including some newly released phones. It was released on October 15, 2010. One month after the initial release on Android, Rovio Mobile began designing a lite version of the game for these other devices. In early 2010, Rovio began developing a version of "Angry Birds" for Facebook. The project became one of the company's largest, with development taking over a year. The company understood the challenges of transplanting a game concept between social platforms and mobile/gaming systems.