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) by critics for its success for leveraging a combination of addictive gameplay, comical style, and low price into a viable franchise with long-term potential for profit. The game's popularity has led to the production of additional versions of "Angry Birds" for personal computers and gaming consoles, as well as a market for merchandise featuring its characters, a feature film and several seasons of television cartoons. With the "Angry Birds" series having a combined tally of over 2 billion downloads across all platforms as of January 2014, including both regular and special editions, the game was called "one of the most