This is an addon now released for Amnesia: The Dark Descent. It allows you to play as your choice of one of the 6 main characters of My Little Pony in both the campaign as well as custom stories.
The full release of my Mane Six Mod allowing your choice of a different player character than Daniel. Includes all six of the main characters: Twilight Sparkle, Applejack, Fluttershy, Rainbow Dash, Pinkie Pie, and Rarity. Compatible with pretty much any custom story, however it might affect your immersion.