Unlike the standard Guitar Hero II developed by Harmonix, the "Extreme" series is an unofficial, fan-made modification. It utilizes the core engine of the original game but replaces the standard 64-track setlist with custom songs and revamped visuals.

GUITAR HERO II (Extreme vol. 2) - playlist by 'ᵐᵘⁱⁱᵐ | Spotify

Guitar Hero 2 Extreme Vol 2 is a popular fan-made modification (mod) for the original Guitar Hero II