If there was a game about Sephy, i would be a very, very happy gamer. =D
And to keep it interesting, rather than just playing as him the whole time, in certain parts of the game you would play as one of the Turks, and have a decent party.
It could actually just be the original storyline--but through the eyes of the antagonist and the rivals of the original heroes. We'd have a different look on what happened, and may even have some of the question we have in mind solved (such as; who was Sephy's real mother, Jenova or Lucrecia?)
And plus...being a one-man army is pretty damn awesome, and it would be quite an interesting change to the world of Final Fantasy.
