Hi,
I'd say "Yes", horror games might enjoy a small boost.
When I released a science fiction type game with horror elements, it did better in terms of traffic to the page, than the pages to some of my other releases.
(Although - it's harder to go by statistics about it now, since I released a lot of my stuff into one collection at this point.)
Edited to add: The boost I'm talking about is a community-given boost (in my opinion) - not a site based one.