Angry Birds (video game) featured app on the UK App Store in February 2010 and quickly reached No.1 there, it reached the No. 1 spot on the paid apps chart in the US App Store in the middle of 2010 and then stayed there for 275 days. The initial cost to develop "Angry Birds" was estimated to exceed €100,000, not including costs for the subsequent updates. For the iOS version, Rovio partnered with distributor Chillingo to publish the game to the App Store. Chillingo claimed to have participated in final game polishing, such as adding visible trajectory lines, pinch to zoom, pigs' grunts, birds'
Angry Birds (video game) for any unused birds. Upon completing each level, players receive one, two, or three stars depending on the score received. Players are encouraged to repeat any previously beaten levels in which the full three stars weren't awarded in order to fully master them and earn the full three star rating. In early 2009, Rovio staff began reviewing proposals for potential games. One such proposal came from senior game designer Jaakko Iisalo in the form of a simulated screenshot featuring some angry-looking birds with no visible legs or wings. While the picture gave no clue as to what type of game