No Good Guys of Goody Goodness or Puppy Kickers Anonymous. Even the 12 foot tall living warmachines have some redeeming values. When in doubt, reference the real world.
No godmode characters. A powerscale will be established at some point, but as a general rule of thumb, everything dies.
No edgelord broodmonger characters. Any given character is allowed to have (HARD MAXIMUM) 1 angsty trait.
Use tropes carefully and softly. Its total okay to borrow a loose structure, but you are going to be exiled if there is a wizard school named Mogmorts and its run by the absent minded but powerful headmaster, RuffleRorf.
If you use artwork that isn't yours, REFERENCE IT.
If you have an idea to change something that is already set, then talk with the group first.
No lore frankensteining. Keep the bloodline pure. Yes Cthulu is cool. No, the stonelords do not worship him.
On that note... Feel free to build religions but do not hard and set affirm the existence of any diety. Just like the real world, who the fuck knows if gods exist.
No Deux Ex Machina (It was only good in Medea) or useless Mcguffins. Magic does exist, but no one can go super saiyan.
Everything must have a purpose somewhere. If something just exists, then tie it into something else. Put them to war with the Stonelords. If you cant find a good reason for something to exist, cut it
Similarly, interconnect. If there is a rebel faction, dont have it JUST be a rebel faction. Connect it to something else. France and Somalia talk too.
Im saying it now, the Stonelords are the top of the totempole. The universe is named after them.