Downloadable content
Harmonix aimed to provide a wide range of music to players through additional content, stating that "Rock Band" is a music platform for discovering music. The developer released new songs, compatible with both games, through regular weekly downloadable content (DLC). including various singles, artist packs featuring three or more songs from the artists, and full albums. Downloadable songs are compatible with "Rock Band" and "Rock Band 2". A portion of the downloadable song catalog is also compatible with "Lego Rock Band", based on the songs' appropriateness for the game's family-friendly content rating. While "The Beatles: Rock Band" also supports downloadable content, the game does not share such content with the other "Rock Band" games, nor can it use content from the other "Rock Band" games. "Green Day: Rock Band" does not have its own catalog of downloadable content but a select number of songs from the "21st Century Breakdown" album were released to the Music Store prior to the game's release. These songs integrate with "Green Day: Rock Band", enabling the player to play the complete "21st Century Breakdown" album in the game. Downloadable content released on or after October 26, 2010 is restricted for use with "Rock Band 3", "Rock Band Blitz", and "Rock Band 4" while content released on or after October 6, 2015 is restricted for use with "Rock Band 4" only.