About
Frets on Fire X (FoFiX) is a highly customizable rhythm game supporting guitar, bass, drum and vocal gameplay for up to four players, continuing a long line of community modifications to the original Frets on Fire by Unreal Voodoo. It's licensed under GPLv2 and available for Windows and Linux.
How it differs from the original
Extends the original Frets on Fire with bass, drum and vocal gameplay modes (not just guitar) and support for up to four simultaneous players.
Getting started
Follow the project's online installation guide, then prepare song and theme data before starting the game, as covered in the linked quickstart documentation.
History
FoFiX describes itself as "the continuation of a long succession of modifications" to the original Frets on Fire.