Both games have captured the imagination of a music industry desperate for not only new sources of revenue but also for products that make music fans excited again. The games\' on-disc soundtracks license 125 tracks between them, and music itself is treated as the star of each game - fans virtually play along using a variety of instrument-based controllers and in-game prompts.

Both titles allow fans to buy and download additional tracks not included in the original game via an online store accessible directly from the game console, with record labels getting a cut of each. Prices and availability have not yet been announced for either game, but the downloadable songs for Guitar Hero II cost $US5 ($NZ6.50) for a pack of three - and moved more than 650,000 units (totaling more than 2 million songs), according to Activision.

Guitar Hero is the incumbent, in a sense. The first two installments of the franchise sold a total of 6 million units, a bona fide blockbuster for any game genre but particularly eyebrow-raising, considering that the game\'s publisher (RedOctane) and developer (Harmonix) were relatively niche players in the videogame industry.

Shortly after, Activision acquired RedOctane specifically to retain the rights to the franchise and has since put out an Xbox 360 version of Guitar Hero II as well as the newly launched Guitar Hero III. Meanwhile, MTV Networks bought Harmonix and together developed Rock Band, tapping Electronic Arts (EA) as the publisher.

Game industry analysts almost uniformly predict that Guitar Hero will sell more copies as a result of its earlier release date and established franchise as well as its lower price (about $US70; Rock Band costs $US170) and broader availability. (Rock Band is limited to PlayStation 3 and Xbox 360, while Guitar Hero includes both platforms plus the popular Wii and older PlayStation 2.)

TRYOUTS FOR SHOPPERS

But Rock Band isn\'t making it easy. The same weekend that Guitar Hero launched, the backers of Rock Band set up demo stations in Best Buy stores across America, allowing shoppers to demo the game in-store well in advance of the release, and similar stations will appear in Wal-Marts soon.

Meanwhile, Activision has given Guitar Hero the kind of prelaunch treatment expected from only the biggest blockbusters. It established an online community site where fans could preview tracks and get behind-the-scenes footage of rockers such as Slash and Tom Morello filming the motion capture for their in-game appearances. It has placed all the music ever licensed for the franchise on iTunes in a special Guitar Hero Essentials section. It even commissioned the Sex Pistols to record a new version of Anarchy in the UK exclusively for the game.

But no matter which sells the most this holiday season, the music industry will emerge as the biggest winner. Both games represent new platforms for how music is sold to fans. Labels can coordinate with the games\' developers so that the latter also release new music on a new album\'s street date - or even in advance of it.

\"We view this as not just a game title but a music entertainment platform,\" Harmonix CEO Alex Rigopulos said. \"We\'re already actively in discussions with record companies about releasing new game content day-and-date with major new releases.\"

Rock Band and Guitar Hero \"bring our artists\' music to a new generation of fans and offer longtime fans a whole new way to interact,\" said George White, senior vice president of strategy and product development at Warner Music Group. \"This is more than a way for us to promote our artists; it\'s a promising new channel for the distribution of music.\"

If the platform proves successful, expect other game developers to get involved as well.

\"I wouldn\'t be surprised if some of the bigger names try to jump in some way,\" IGN analyst Nick Williams said. \"I\'m sure they\'re all looking into developing their own spin on it.\"

And while rock has led the way so far, expect hip-hop, country and other genres to receive their own versions of these games, complete with controllers specific to each, as early as next year, if the current versions sell as well as expected.

\"This is the beginning of music and film and TV becoming interactive versuss linear forms of entertainment,\" EA head of music Steve Schnur said. \"Interactive media is the only way media is going to be delivered in the future.\"