While there is no official "free" version of Guitar Hero III: Legends of Rock from Activision, you can access the game or its content through several safe, community-driven methods for PC.
If you are looking for the "full game" experience with modern improvements, fans have created standalone installers that simplify the setup on modern Windows systems: Guitar Hero III: Legends of Rock Free Full Game...
This is the most popular modern successor. You can download the engine for free at clonehero.net and then add "song packs" that contain the entire Guitar Hero III setlist. While there is no official "free" version of
A massive mod for the World Tour PC port that allows you to import the entire GH3 setlist and play with improved graphics and features. 3. Legacy Downloads Guitar Hero III: Legends of Rock Free Full Game...