Rock Band 2 is a 2008 music video game developed by Harmonix Music Systems and distributed by MTV Games and Electronic Arts. The game, a sequel to Rock Band, has been released for the Xbox 360, PlayStation 3, Wii and PlayStation 2 . Rock Band allows one to four players to simulate the playing of rock music by providing the players with peripherals modeled after musical instruments (a guitar peripheral for lead guitar and bass gameplay, a drum peripheral, and a microphone). The gameplay in Rock Band 2 is nearly identical to the original Rock Band, while also comparable to that in Guitar Hero.
The game disc features 84 songs, all of which are master recordings. In addition, the game supports existing downloadable content from Rock Band, as well as tracks which have been exported from other Rock Band game discs. Twenty additional tracks were released exclusively for Rock Band 2 as free downloadable content after the game was released. A redeemable code that allows the player access to these songs is included with new copies of the game, except for the Wii version, where no code is required.
With Rock Band 3, Xbox 360, PlayStation 3, and Wii players can export 70 of 84 songs by purchasing a Export Key for $9.99/800 Microsoft Points/1000 Nintendo Points. The 9 songs from Harmonix-based bands are not offered in the export package; however, these songs are offered in a free DLC package for the PlayStation 3 and Xbox 360, released on January 4, 2011. The export for the Xbox 360 and PlayStation 3 versions requires the code located on the back of the Rock Band 2 instruction manual; this is the same code used for the redemption of 20 bonus downloadable songs that were released shortly after Rock Band 2's launch. EA support will accommodate users who may have lost their previous code. Wii owners only need to have a Rock Band 2 save file present to perform the export function; however, tracks are downloaded individually. 
Each of the 84 songs is categorized on-disc by difficulty (0 dots being the easiest and 5 red dots being the most difficult) for each instrument, as well as the entire band. Players can also choose from one of four skill levels (Easy, Medium, Hard, and Expert). Unlike previous installments in the Guitar Hero and Rock Band series, the nine bonus songs are integrated with the other 75 songs in the game's track listing. These additional songs consist mostly of bands formed by Harmonix employees, as well as lesser-known bands and local bands from near Harmonix's headquarters in Cambridge, Massachusetts or from Boston.