Angry Birds (video game) crates and rocks are incorporated into the structures, and power-ups may be used to enhance the birds to attack hard-to-reach pigs. Also in the levels, players can unlock bonus levels by collecting golden eggs. There are several different types of birds used in the game, distinguished by their color and shape. In the earliest levels only the basic red bird is available. As the player advances through the game additional types of birds become available. Some birds are effective against particular materials, and some have special abilities that may be activated by the player while the bird is airborne. For
Angry Birds (video game) features not available on the smartphone versions. One day after the Windows version was released, the Mac App Store launched, with one of the first offerings being its own version of "Angry Birds". Ports of "Angry Birds" have also been proposed for the Wii and Nintendo DS systems, with the former becoming realized through "Angry Birds Trilogy" (see below). A 3D-enhanced version of the game was proposed for release on the LG Optimus 3D in October 2011. The popularity of "Angry Birds" has helped spread the game to other devices that were not initially designed as gaming machines. Barnes &