For the past few weeks I've had this quirky concept in my head. I would have rather presented it to you with an example, but perhaps it's better to hear what you think first. (And get an answer to that all-important question of course: Has this been done before?
My concept involves 'music video' games. Not video games that involve music, but rather music that involves game.
It would be the gaming equivalent of a music video. So, the games are naturally short—as long as the song of choice lasts. You could do loopings to extend the playthrough of course, but that's a missing the point a bit.
The point, being that everything in the game is accentuated by the music. This can mean that the shape of the level reflects the melody and chord progressions etc., but it could also be the lyrics that determine whatever happens in the game.
The examples I have in mind that excite me most are songs with outlandish lyrics, and also the repetition that can arise naturally from a song's arrangement (verse, chorus, verse, chorus, bridge, etc.).
What I'm not still sure about, are goals and scoring, and if those are even needed. Perhaps these games could simply stand alone as 'experiences'.
I recently came across something very similar to this concept, although I have something 'gamier' in mind. Nevertheless, it's very beatiful and worthy of your time... I think. http://soytuaire.labuat.com/
(It's an interactive music video where you control an Okami-like brush stroke with your mouse cursor.)