I do not know the full story, but I believe that if you steal copyrighted content and add it to your story, then it can be held for copyright. Copyrighted content will really come under a licensed use kind of thing.
The problem is because we make things for free here, do not charge or whatever, most times it does not count as stealing, rather just to the point of how you got it. I think no matter what however whenever you use other things without proper permissions, you MUST give credits to them.
Edit: One thing I can say is use other music for imagination and inspiration. Final Fantasy VIII's soundtrack focuses entirely on mood during the scenes of the game. Though is not ever much of a horror concept, a castle one is given in The Castle on Disc 4. You can look and listen at other tracks and try and get a sense as to why they communicate a message so well, then make your own. That way, it's your own content and evades copyright