Assuming you don't want the sugar coated answer, I have read and played your idea before... it's like every other game or work of fiction. What differentiates it? I'm sure you will have an immediate answer for me, but really stop and think about this question. Take Final Fantasy VI for instance. It had several pretty good ideas, borrowed a few good elements (arguably from Star Wars or something Star Wars was based on), and had a really good implementation. Now that is a game.
I agree on this one. As Shane C said, it's not a really original story. Well at least the start. You could do a good job on the character, the world building, the gameplay etc... (Execution if everything as said someone ;) ) But I don't find the premise attractive.