"[Guitar Hero IV's] not just about guitars," Kotick told IGN. "We'll include a lot of other instruments, vocals. It will help us expand internationally. It's the first game we've had in which we can use local content and local bands."
The runaway success of the multi-instrument rhythm game Rock Band, which includes drums and vocals on top of guitars, had led many to speculate that the traditionally guitar-only Guitar Hero franchise would eventually see the addition of more instruments.
Guitar Hero IV is expected for release this fall, as the third Guitar Hero title announced by Activision for release in 2008. The first two were announced as Guitar Hero: On Tour and Guitar Hero: Aerosmith.