[Coda]

It all depends.

Do you want to discuss the song being performed? Music Discussion.

Is the purpose of this to demonstrate your creative skill? Art Discussion.

Do you want to talk about the game you're doing this in, beyond just this specific performance? Gamer Heaven.

Do you want to discuss the general concept of playing music in a game? That could go in either Music Discussion or Gamer Heaven with no problem.

There's enough overlap in these categories that you have some flexibility in topic after the thread is started regardless of WHERE you start it, so choose from the three based on what your intent is.