Frets on Fire is an open source rhythm game for Windows XP, Mac OS X, and Linux platforms. It was first released on August 3, 2006 and is hosted by SourceForge.net. The game is licensed under the GNU General Public License. Developed by Sami Kyöstilä and Joonas Kerttula, Frets on Fire is a clone of Guitar Hero.
Frets on Fire is meant to be played on your keyboard. You are meant to hold your keyboard as though it were a guitar, using (by default) the F1 through F5 keys as frets, and the enter key to strum. These can easily be changed (personally, I have my strum key set as pause, so that it too is at the bottom of the "guitar"). The game also features joystick support. What this means, is that if you get yourself a USB guitar intended for use with Guitar Hero II for the Xbox 360 and a few extra drivers, you can rock out with a real fake guitar to Frets on Fire.
Gameplay is virtually identical to Guitar Hero. Scrolling notes move towards the bottom of the screen, and the corresponding fret must be pressed and strumed as they pass through indicators (shaped like keyboard keys in Frets on Fire) at the bottom of the screen. Consecutive notes build up a score multiplier of up to four, missed notes reset the multiplier. Hammer on and pull off (HOPO) notes, like in Guitar Hero, are also present (an entire sequence of notes can be played by strumming correctly on the first, and then simply pressing frets for the rest without bothering to strum again). There is no Star Power as in Guitar Hero, but there is also no tilt detection in the average computer keyboard.
When first downloaded, Frets on Fire will have a paltry library of three songs. However, songs can be imported from Guitar Hero I and II, and better yet custom songs can be made. These are available through various locations as massive torrents with hundreds of songs apiece. I haven't quite figured out the song editor, but once I do, I will definitely be rocking out to some George Thorogood.
If you can get over looking a little silly at pretending your keyboard is a guitar, Frets on Fire rocks. It rocks almost as much as Guitar Hero. Frets trumps Hero in two important aspects: first, it's free. It's open source and runs on Linux; you'll never pay a dime for it. Second, it's for your computer. Those of us with no Playstation 2 or Xbox 360 who are just dying to play some fake guitar can fake rock with the best of them. An unfortunate side effect is that the game tends to make you want to play real Guitar Hero even more. But fear not, for Guitar Hero III comes to the Wii this fall.
Download it here: http://fretsonfire.sourceforge.net/. Keep on Rockin' in the Free World