Is their an audience for...

[Bridge]

Sorry, I'm not familiar with any custom stories. There is a shortage of Penumbra Let's Plays though, you probably stand a better chance of standing out if you do a LP of that. If you absolutely want to do Amnesia then just do Amnesia and hope for the best. The difference between a good LP and a bad one is not really how good (or how overdone) the game is, it's how good the commentary is.