Angry Birds

Angry Birds is a puzzle video game developed by Finland-based Rovio Mobile. Inspired primarily by a sketch of stylized wingless birds, the game was first released for Apple's iOS in December 2009. Since that time, over 12 million copies of the game have been purchased from Apple's App Store, which has prompted the company to design versions for other touchscreen-based smartphones, such as those using the Android  operating system, among others.

In Angry Birds, players take control of a flock of multi-colored birds that are attempting to retrieve eggs that have been stolen by a group of evil green pigs. On each level, the pigs are sheltered by structures made of various materials such as wood, ice and stone, and the objective of the game is to eliminate all the pigs in the level. Using a slingshot, players launch the birds with the intent of either hitting the pigs directly or damaging the structures, which would cause them to collapse and kill the pigs. In various stages of the game, additional objects such as explosive crates and rocks are found in the levels, and may be used in conjunction with the birds to destroy hard-to-reach pigs.

There are several different types of birds used in the game. In the earliest levels, the basic red bird is the only one available. is the player advances through the game, additional types of birds become available; some of these birds are more effective against particular materials or they have special abilities that are activated by the player after the bird has been launched. For example, a blue bird can separate into three birds, a black bird explodes and a white bird can drop explosive eggs. The pigs themselves also appear in different sizes. While small pigs are relatively weak and are easily destroyed either by direct hits or by debris from the damaged structures, larger pigs are able to sustain more damage. Also, some pigs wear helmets as armor, making them more resistant to damage, while pigs with crowns can take the most damage.

Each level starts with the number, types, and order of birds pre-determined. If all of the pigs are defeated by the time the last bird is used, the level is completed and the next level is unlocked Points are scored for each pig defeated as well as for damage to, or destruction of, structures, and bonus points are awarded for any unused birds. Upon completing each level, players receive one, two, or three stars, depending on the score received. Players may re-attempt unlocked levels as many times as they wish in order to successfully complete them or to earn additional points and/or stars.