Innovation Versus Formulaic Gameplay

[E-Man]

I can agree why being too different from the original formula could cause trouble. Take Paper Mario: Sticker Star for example. It would have been a fine game, but the fact that they changed several key elements of the game that made it so good (and I don't mean just completely changing the RPG system). Basically, when creating a sequel, you need to preserve what made to original very great and build up on it in areas that would benefit the most from it.