The controller.

Activision have revealed that DJ Hero will feature over 100 songs that have been mixed into more than 80 "exclusive, original mixes" by "superstar" DJs such as DJ Shadow, DJ Z-Trip and DJ AM. Artists to be featured in the game include Black Eyed Peas, 50 Cent, Justice, Marvin Gaye, Beck, Beastie Boys and N.E.R.D.

Other details have also been revealed, including the fact that many real-world DJs will be making an in-game appearance, along with the fact that users can engage in competitive multiplayer, and also use a guitar controller to play "DJ-guitar exclusive mixes".

Allowing gamers to "play along" to music from a variety of genres, DJ Hero promises to "excite dance club music fans" with hip-hop, R&B, rock, and electronica.

DJs who contributed to the development of the game, DJ Shadow, DJ Z-Trip and DJ AM will appear as in-game characters (probably for DJ battles or somesuch) and have each created "multiple exclusive mixes" that will appear in-game.

DJ Hero promises to immerse players in the DJ culture, and a "sea of music". The controller features a rotating turbntable, sample buttons, an effect dial, and a cross fader, allowing players to scratch, blend, crossfade and sample music.

Multiplayer will be "euphoric", allowing two DJs to battle against another, or allow another player to emcee over any track with a microphone. Those who have a guitar controller will be able to join in on the fun in exclusive "DJ-guitar" mixes. How exactly this will work has not yet been revealed.

DJ Hero is in development for the PlayStation 2, PlayStation 3, Xbox 360 and Nintendo Wii. A release date has not yet been confirmed, but it is expected at some point this year.