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) called the game "an addictive, clever, and challenging puzzler", and "Pocket Gamer's" Keith Andrew said "Angry Birds" is "a nugget of puzzling purity dished out with relish aplenty". Jonathan Liu of Wired News wrote that "going for the maximum number of stars certainly adds a lot of replay value to a fairly extensive game". Reviews for the first versions of the game that did not use a touch-screen, the PlayStation 3/PSP version and the Windows version, have also been positive, but with some disagreement over the different interfaces. Will Greenwald of "PC Magazine", in his review of the PlayStation Network