When Guitar Hero: On Tour was announced--after nearly a year of rumors--it sounded like the perfect combination of the two-game phenomenon. Using a four-button attachment, it would bring Activision's billion-dollar rhythm franchise to Nintendo's DS handheld, which boasts a worldwide installed base of 41 million users.

　　Now, apparently perception has become reality. Despite mixed reviews--including a 6.0 from GameSpot--Guitar Hero: On Tour has sold more than 300,000 units in North America in just seven days. According to Activision, the game's debut marks "the largest North American launch for the Nintendo DS in the company's history by more than a factor of eight." Previous high-profile Activision DS games include Tony Hawk's Proving Ground, Spider-Man: Friend or Foe, and Call of Duty 4: Modern Warfare.

　　Rated T for Teen and priced at $49.99, Guitar Hero boasts 25 songs, 20 of which are new to the series. These include Rick Springfield's "Jessie's Girl," ZZ Top's "La Grange," and Steve Miller Band's "Jet Airliner." Besides the standard single-player career mode, the game boasts several wireless modes, including guitar duel, co-op guitar/bass play, face off (players alternate riffs), and pro faceoff (play the same notes).