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) exclusive content when played on Chrome, such as exclusive levels and the so-called "Chrome Bombs". The version includes offline playability and features 60 FPS gameplay with a selection of graphics settings to accommodate a variety of hardware capabilities. In October 2011, during Nokia World 2011, it was announced that "Angry Birds" would come preloaded in Nokia's Asha series of Series 40 touch handsets, aimed at emerging markets such as India, China and South Africa. In December 2011, Rovio released "Angry Birds HD", "Angry Birds Seasons HD" and "Angry Birds Rio HD" on the BlackBerry PlayBook tablet from Research In Motion.