Because it's going to be spooky season:
Horror theme, because it's a genre that isn't too popular but seems to have plenty of people wishing for more of. Bonus points for eldritch horror because tentacles.
-dere theme, because we're still full of weebs here and every loves their -dere types. The story would have to revolve around a character who fits one of the standard -dere types. Bonus points for yandere because it's going to be spooky season.
Dramatic personality theme. This one is a bit harder to explain. Originally on the Discord server, I suggested a chuuni theme. But because that might be a bit limiting, it could be expanded to super dramatic personalities in general. Like taking a character type and pumping it up to an unrealistic and silly extreme. Chuuni is still the most fitting, though, because they're all about dat darkness and it's going to be spooky season.