With "Guitar Hero: Aerosmith" just weeks away from release, the much-rumored Metallica version of the game appears imminent. An analyst at Wedbush Morgan Securities found reference to the upcoming, but as of yet unannounced game in a recent SEC filing by Activision, publisher of the Guitar Hero franchise.

There's been no official announcement from Activision, and the exact timing of its release remains unknown. However, speculation suggests that it will come out sometime after the release of "Guitar Hero: On Tour," otherwise known as Guitar Hero 4 -- which like rival "Rock Band" will feature a full compliment of instruments beyond the guitar. The title is expected this holiday season.

"Guitar Hero: Aerosmith" is slated for release June 29. Unlike other "Guitar Hero" games, which feature scores of tracks from multiple artists, the Aerosmith expansion will include primarily that band's catalog, along with a smattering of songs from bands that Aerosmith wanted included.

The game "storyline" features Aerosmith's rise from smaller venues in Boston to large stadiums, with motion-capture animated versions of all band members.