Music-based games have become as vital as iTunes itself

Tapping on fake instruments and screeching into microphones connected to video game consoles has become lucrative for both the music and gaming industries. Downloadable tunes for music-based games "Guitar Hero," "Rock Band" and "SingStar" have become as vital as iTunes itself - and one of the last ways to expose youngsters to classic rock.

The genre will evolve again later this month when game publisher Activision and developer Neversoft release "Guitar Hero: Aerosmith," the first such play-along rhythm game pegged to one music group, instead of featuring a multi-artist compilation more akin to one of those "Now That's What I Call Music!" albums.