No rules really beyond simple courtesy. (If you don't agree with someone, discuss, don't declaim.) My one suggestion as moderator is that the hordes of writers with a perfectly natural desire to attract readers might consider participating in some discussions before touting the value of their own work. There are threads already set up for new releases, reviews, interviews, that sort of thing.
Other than that ... just have fun. And welcome to the group. There are some terrific people here, and we've had some great discussions. Enjoy!
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This group is dedicated to an appreciation of important works of world literature, both classic and contemporary, that happen to fall into the category of Dark Fiction.