It probably also needs to be said that the idea of fangames are dying down a bit, with the booming success of indie game dev stories now, and also the larger rise of copyright issues. Why spend several days and months working on a fan project you can't sell and can potentially get Cease and Desisted, when you can do something relatively original and turn it into a profit, so you can use that money for future projects?
My suggestion to you: Scrap the idea of it being a fangame by swapping out the characters and settings for something original. Then it can be an "inspired by" game that you can actually sell and not have to try and hide behind a vague fair use clause.
My suggestion to you: Scrap the idea of it being a fangame by swapping out the characters and settings for something original. Then it can be an "inspired by" game that you can actually sell and not have to try and hide behind a vague fair use clause.