I've done worldbuilding and extensive plotting for a Book 1 based around a "detective" (not a literal detective but someone who fills that role) who hunts and resolves (neutralizes) occult objects. The character came from a different project – an anthology of oral ghost stories told from an alternative narrator – so I didn't bother to check what else had been previously created in this "space" before I started plotting a stand-alone novel around him. It's not that I was trying to be original, but my personal-genre is sci-fi so I didn't realize that "occult detective" is a well-established genre dating back over a century.
Probably a bad idea but I got curious about how everyone else has treated the subject. I downloaded the OG stories from Project Gutenberg, found tons of examples online from comics to TV, and explored reviews for current novels on Goodreads. It's a wide-genre but the early years are essentially "My stars, Col. Hastings, there are such things as ghosts!" to today's "Mary Sue Wolfenstein is a shapeshifting Wicca werebat lawyer with an alien vampire boyfriend and an undead cyborg partner who is hunting a serialkiller"…. It honestly feels like the whole genre (or at least the popular surface) has jumped the wereshark.
The awkward thing was that I could place my grumpy retired detective within the popular timeline of that genre-evolution, as a character somewhere in the early-to-mid 1970s. I was toying with setting it in the past, but that settled it. I set the story in 1975 so his life could span certain historically relevant events in my alterna-world. (Maybe it's just media I grew up with. He fits that era and the scope of the conflicts do too.)
That doesn't actually solve my issue that this genre (with which admittedly I am not an expert) now seems played out to an absurdist degree. My story is just never going to be the modern cross-genre anything-goes romance-adventure kind of stuff that seems to be commercial and splashy. My story is set in a much smaller world, semi-historic, where not "every mythology" is true.
I feel like I have to do extra worldbuilding just to undo current genre-bloat. I'm also afraid that I'm actually writing an outdated story with a quaint old-timey character that will seem like a throwback to the genre-savy.
How do I ratchet down reader expectations within an existing genre?
~ or, alternately ~
How can I be more confidant about carving my own niche within a genre that has already been widely played?