Cant say its very orginal, the whole 2 sides, one bad, one good is kinda old, boring, and Done. Need more ideas.
The game itself is probably good though .....
Now that is true. The cool thing is, even though he is a dark side, he still acts like the prince and he embodys traits that the prince already had within him, like rashness, anger, slighly sadistic, and he also thinks and makes comments similar to things the prince would say. But I still agree with you that the whole idea has been done many many times before.