During the Solo Career mode, the player will also encounter three Boss Battles, a new mode introduced in Guitar Hero III, at the ends of three tiers as listed below, prior to performing the Encore song. The player(s) must complete some or all of the songs in one tier (based on the career difficulty selected), including the Encore, to access the next one. These songs are arranged in eight sequential tiers based on their relative difficulty. Guitar Hero III features 73 songs spread across both the Solo and Co-Op Career modes.
