Aspyr Media today announced that Guitar Hero III: Legends of Rock (site not updated) is slated for shipment on Mac and PC platforms this fall. The sequel to the wildly popular Guitar Hero II includes vast new content, and features a multiplayer action-inspired battle mode as well as tough boss battles. The game offers a host of exclusive unlockable content that includes more than 70 songs and more original master tracks. Expanded online multiplayer game modes allow PC and Mac users to play head-to-head against players around the world across either platform. Guitar Hero III: Legends of Rock's battle mode will feature broken guitar strings, increased difficulty for opposing players for short periods, amp overload that makes notes difficult to read, and more (pricing was unavailable).