Activision has announced that Soundgarden’s greatest hits album will be included in the first million launch units of US copies of Guitar Hero: Warriors of Rock. European gamers will not get anything with their copies. We’re not sure if the album will be DLC in the UK or not yet either. Soundgarden’s new single, Black Rain, will also debut on the Warriors of Rock disc. Guitar Hero: Warriors of Rock will be released on the PS3, 360 and Wii this September.