There's a fanfic idea that I've been bouncing around in my head for awhile, but it's only now that I've felt up to actually attempting it.
The basic idea behind it is this - I would take the VN/Galge-style narrative, with its diverging romantic routes and numerous alternated endings, and apply it to Puella Magi Madoka Magica.
It would be wrote from the perspective of Madoka (1st Person narration), and would follow the anime narrative closely, except the reader could make choices (mostly verbal) at key moments to shift the story in different directions, and potentially move Madoka into romances with other major characters. Different choices can "raise" or "lower" Madoka's level of affection with different characters, and that can open up (or close off) potential yuri romantic routes. So it's important for readers to keep track of the choices that they make as that will make a big difference later on in the fanfic. You can, of course, read what the results of each choice is, but pay special attention to the results of the choice that you make, as those are the results that will stick with your initial read-through of the fanfic.
Anyway, I hope that this is a fanfic that Madoka Magica, yuri, and VN fans will all enjoy!
You can read it
here.