So a new mod for Source came out called Flesh which is horror and stuff. I liked it and I haven't finished it yet but so far it took me 2 and a half hours to get the the third map and I believe there are 5.
Sometimes you forget it's actually Source cause they've done some nice changes to the engine using Hammer entities mostly such as the 3rd person camera.
It's a mix of Silent Hill and Siren and I think you should all give it a go:
http://www.moddb.com/mods/flesh
Downloading!