I think I've mentioned this a couple of times but the early design work for wktd actually was for a tabletop rpg, though I never got as far as making any actual systems for it. My fantasy was that each player would get their character sheet in the form of a folded up zine, and they would know things about their character and the game that other players couldn't (anyone could see the front and back pages of your zine, but only you could read the inside of your own) and there would be secrets, like your true form, you could only learn once you had fulfilled the conditions that let you unfold the pages and see what was behind them. This is the sort of idea I might make for fun if I had a lot of time and didn't need to make any money off of it.
Anyways, I would probably have looked at Monster Hearts or Apocalypse World first for designing that game. PBTA games are focused on player-player conflict and interaction with the MC throwing stuff at them to make things interesting. They're not DM-less games, but they're pretty close, and my ideal vision for a WKTD type game would be that it didn't need a DM, because each player would have goals and instructions both public and hidden that would be enough to motivate the players to get into it with each other such that the game stayed interesting. You could even have a random table of prompts and roll some dice and get any of the branches in that game like "a bunch of stupid assholes come up and boss you around" and the players have to decide how they're going to deal with it, and ideally those mechanics lead to someone getting left out, which pushes them towards the devil and the rest away.
Monster Hearts has lots of really cool mechanics that push players to act in specific ways that make a lot of messy drama; I would probably take those as a base and institute mechanics that say, reward you for being a prude or and calling others out, scrutinizing your own thoughts and behavior, evading social encounters without anyone humiliating you, etc. I think to be successful, the rules of the game have to pull you in two opposing directions, and for the players to be heavily punished for acting in the way they actually want. There should be a lot of risk involved in following your real desires, and it should require a lot of trust. The players are already going to want to work together and be friends, so the rules have to take on the role of being the villain, including representing the parts of the players they'd rather not have.
DM-less is a pretty ambitious design goal, but if anything it felt like the focus on player interaction would be hindered by a MC, because the whole thing about wktd and its conversation with magical girl stuff is: the enemy is the one who becomes the outsider. Magical Girl shows have a monster of the week we can all come together and defeat, but in the wktd world, like ours, it's another person. Everyone is trying to not become the scapegoat, and you need to push the characters to fight and exclude or everyone coming together to feel real and earned. For a wktd game you need a lot of emotional pvp mechanics and basically no combat mechanics. I mean, they never even fight the monsters in the end. They blow them up in one hit because that's how easy it is to triumph over evil; what they do in the true ending is much harder.
Like, you don't get to go out and shoot Society and Internalized Homophobia with a gun. These are parasites that live inside you, and they make you hurt each other, and killing them without someone else's help is impossible. I think the duty of the Rules is to represent your struggle authentically, and the duty of the players is to find a way out, and it shouldn't be easy. Anyways, this is just what about wktd feels important to me, which is not necessarily what you're going for in what you want to make. Regardless, good luck! Hope this is helpful for inspiring you.
