I don't know for sure for how long this has been known; but quite frankly, this is the first time I've bumped into it. Can't say for sure whether Frets is a clone of the PlayStation and recently Xbox 360 title, or vice versa because I'm not sure whose idea was first out, but they're identical in terms of gameplay. Frets on Fire looks more like the wireframe of Guitar Hero (a development stage were the game doesn't have the texture of the objects done).

Wikipedia says Frets on Fire is a free, open-source music video game and the winner of the Assembly demo party 2006 game development competition. It too says "Frets on Fire is a Guitar Hero clone where the player emulates playing the guitar section of a song." Notes appear on the screen, synchronized with the song, and are played by holding the correct "fret buttons" from F1 to F5. So five notes/buttons just like in Guitar Hero. Pressing the "pick button," which is either Enter or shift (as the player wishes) at the right moment will result in streaks of correct notes increasing the point multiplier, but a single missed one resets it.

Well, that last part makes it sound kind of dull if you ask me. Guitar Hero is not like that from this point of view. Missing one note or two will only result in a lower ranking and only if you totally suck, you lose. It's a game, not a life and death situation. Frets on Fire is also very simple, as there is no actual goal to meet for any given song. Players just try to make a good score and scores can be uploaded and compared at, the official website of the game. However, there are quite a lot of options and customization features:

- there are 4 difficulty levels to be chosen from: Supaeasy, Easy, Medium, and Amazing;
- a tutorial option as well (in games like this you really need to visit the tutorial first)
- custom song editor - that you don't get with GH;
- 3 standard songs, along with the ability to download songs made by others or your own songs, so naturally you can import Guitar Hero or Guitar Hero II songs too;
- it has joystick support, in case the F buttons on the keyboard puzzle you;
- Xfire instant messaging service currently supports Frets on Fire;
- the game has modification support.

So, seeing these differences proves in some way that Frets on Fire isn't an exact Guitar Hero replica, but the resemblance is striking, as you'll see in the video below. Maybe the recipe is so good that you can't have this kind of game any other way. Still, there is one question that remains unanswered: "who's copying who here?"