@Derp - If only if was more like Supernatural! I'm actually rewatching the series and so inspired to run plots I can't hardly see straight XD
The magic of Supernatural is that it doesn't take itself seriously. There's room to have fun and be goofy and go to those crazy, wacky places with it. But then you also have these amazing NPC's, like Pestilence, Death, and Loki. Death's entrance to the series is just... Amazing.
It could very well be different thresholds for grimdark, too. Me, I can watch Saw and munch blue-rare steak like 'wut?'. I try to temper that when I ST because not everyone has a cast iron stomach and enjoys that kind of gore. Or the darkness found in Hostel.
So, if I have this right, it seems like the theme is alright if it's oppressive, but it's more or less up to the ST's, Players, and Staff to try and find that balance between too dark and too campy?
And maybe some 'take it seriously, but not too seriously', otherwise it is too oppressive on an ooc level?
It sounds like this a turning into a case where it falls back on the usual culprits of 1) Staff expectations and flexibility between hardlining theme or being flexible enough for that mix of styles to exist 2) Players and ST's communicating about what they want, need, and expect from a scene(s), and 3) that handy +prefs code @Cobaltasaurus came up with to help people get there and find people that'll play to the level the different player-types are wanting.
I would even toss out the idea of Staff being open to more ideas from players, but players being willing to go to staff with suggestions.
And not just the usual 'what do you want, well too bad we're not doing that' sort of lipservice a lot of games give, but actually implementing the suggestions that come in when you get players to talk to you.