Viacom's MTV Networks, publisher of the new Rock Band, says the music-based video game is selling so well that copies have been flying off the shelves in its first week, according to Reuters.

Downloads are going great, rockband.com is going great with people logging on and downloading stuff from there. It's got a lot of legs, we're in it for the long term, Mika Salmi, head of digital at MTV said. Specific sales figures were not mentioned.

Rock Band allows users to play along with famous bands, using guitars, drums and microphones. The game is designed for multiple users. Its price is $169.99 and comes with 58 songs.

Its main rival for the holidays is Activision's Guitar Hero 3 which sold $115 million worth of games, the publisher said. It shipped 1.4 million copies in its first six days, NPD reported.

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