First released in 2007, Rock Band came about after MTV Networks purchased Harmonix, the creators of the music rhythm series Guitar Hero. Rock Band plays in very much the same way as Guitar Hero, with a scrolling track and colored circles for the player to match in time to music. Rock Band, however, introduced additional instruments to augment the original guitars, including drums, vocals, and a keyboard. This allowed for players to form their own band, with each person on their own instrument. This development lead to these music rhythm games becoming a much more social experience with groups of players, rather than one or two. Because of the association with MTV Networks, Harmonix was able to secure the rights to many more popular songs and artists, leading to a huge song catalog with additional songs that players can download. Since its release, the Rock Band franchise has over $1 billion in total sales.