Thus far there are two I've seen:

Doors by Pixel Berry

&

Equestria's Crippled Daredevil by the same person ^

So far this author is very interesting and is trying like me to create something that's not very common. Which one's have you seen?

I read those like ages ago. They're great.

4865511 The Impossible by Truekry. It is an utterly unique story in which the protagonist Melody Williams actually has an identity crisis by acting like a pony instead of behaving like a human. And to be even more unique the writer had the magic in Equestria seem to have altered her biology enough for her to get pregnant by a stallion.