Frets on Fire is a free, open-source Finnish music video game created by Unreal Voodoo. Players use the keyboard to play along with markers which appear on screen, with the aim to score points, achieve a high point multiplier, and complete a song. Frets on Fire was the winner of the Assembly 2006 game development competition.

The game is written in the Python programming language, and is licensed under the GNU General Public License, although the game incorporates other free and open-source code under other licenses. The game's included song files and some internal fonts are proprietary, and their redistribution is not permitted outside of the Frets On Fire executable.