Guitar Hero On Tour: Modern Hits was announced on March 5, 2009. Reflecting its title, Modern Hits incorporates songs published within the last five years of its release, and the developers had to balance what songs were included in order to make a setlist with a wide appeal. The engine of the game has no major changes, but Vicarious Visions stated that it has continued to work on strum detection on the DS touchpad to meet a wide range of playstyles. The interface, however, has been revised over the previous two On Tour titles to feature a more modernized look (particularly in-game on the touch screen side). The game includes a new single player career progression using "Fan Requests" to create a new non-linear progression through the songs in the games. These were added to help move away from gameplay that was "just going, playing a venue, and then moving on to the next one" and instead to "open the world up". The developers also noted that the Fan Requests helped to tap into the way that players had previously played games in the series, setting their own personal goals for certain songs
Source: Wikipedia, "Guitar Hero: On Tour series", available under the CC-BY-SA License.