What games would you pick that aren't really a part of the horror genre, but maybe have horror vibes, or fall vibes, or something else that makes them really suited for fall?
Darktide is probably the most horror-y of the 40k games with the nurglite hordes and monstrosities, and while not quite scary a well placed daemonhost can make for some tense moments.
Costume Quest is technically past due, but being set on Halloween has big spooky fall vibes.