Ravenloft, for me, boils down to one pretty basic gameplay motif:
Defend the Fort
In many ways, in standard D&D, and blatantly so in 4e, the basic idea is aggressive -- you go somewhere, you change things, you come back better for the experience. You are encouraged to go out.
Ravenloft is kind of the opposite impetus. You stay in, you resist change, and, if you succeed, you are better for the experience -- better equipped to handle it the next time it comes for you. You are encouraged to stay in.
This kind of urge should be as present for the PC's as it is for the window-dressing townsfolk that farm the dirt of Barovia. Namely, the PC's should feel a strong pressure to hunker down, defend a location, and be thankful with nothing leaping at their throat in this one moment, because that could change in the next. You win not by killing all the goblins, but by protecting your local orphanage from the rampages of dark things beneath the stairs -- if you go out to kill all the goblins, you will die. If you just drive them off...then you'll be fine...for now...
The inherent conflicts that I see all boil down to this: in Ravenloft, the conflict isn't between Good and Evil. It's between Bad and Worse, and often these lines are fluid.
#1: Trust No One vs. Die Alone. In Ravenloft, if you try to achieve something on the power of your own heroism, you will fail, and probably be mocked by dirt-farmers for trying. YOU can't do anything by yourself. At the same time, everyone you do team up with will have some big issues (see below) that are likely to endanger you and everyone around you. A PC is constantly torn between working with people who are stabbing him in the back (even if unintentionally), and working alone against things trying to stab him in the face (again, even if unintentionally). Success lies in balancing these -- trust your friend the Paladin of Pureheart too much, and chances are he'll go mad in his sleep and kill you all. But if you don't trust the Paladin of Pureheart at all, he won't be able to defend you from the Zombie Hoard that is knocking down the walls of your medieval shopping mall.
#2: Skeletons in the Closet vs. Zombies in the Streets. In Ravenloft, everyone has their secret sins and problems -- the Dark Powers have fondled everyone's collective soul, and even the most devout priest of Pelor probably does dark things at night in the privacy of his own priory. However, revealing these things, calling them out and making them well-known, is just going to make the problem into something that hurts everyone. If what that priest does becomes known, it will weaken his position, rendering his family, his friends, his entire community, vulnerable. Every PC should have a secret, and the balance should be between hiding that secret (and the danger it does to you) and having that secret revealed (and the danger it does to everyone around you). Success is minimizing the damage you do to everything around you, and still managing to live.
#3: Save Yourself vs. Save Everyone Else. In Ravenloft, one of the big goals has always been "escape." You don't wanna be here, it's a horrible place, and everybody smells funny and sounds vaguely Eastern European. But that's self-interested...you're also a heroic figure, and you want to end this evil blight upon the land, too. This is ultimately the corrupting influence of the plane -- if you save yourself, you "win" but to win in Ravenloft is to become part of its evil and vile nature. If you save everyone else, you "loose", but loosing in Ravenloft is the only way to keep your soul intact. Success in the context of a game with challenges and whatnot means saving as many as you can, and counting that as better than the alternatives (loosing everyone, or dying yourself).
Ravenloft is thus a defensive game of conservation -- you're more the things defending the MacGuffin than the guys who go to get the MacGuffin.
The things discussed mostly here are just corollaries -- the xenophobia is a trait that NPC's and PC's develop to defend themselves against risking trust in someone that they don't know at all. The prominence of villains over heroes is the result of villains being "pure" and the assertive yang-force in the setting, and heroes never being perfect and being the defensive yin-force in the setting.
It ain't just D&D with vampires instead of dragons.
It's totally possible to do this within the 4e ruleset but I am concerned that the 4e team's mandate to make "everything core" ultimately means that we get the same game with different window dressing, rather than a real exploration of what it means to be a different sort of hero. Standard D&D heroes are action heroes --bustin' up heads and takin' names. Ravenloft heroes are of a different sort: They are scared. They are flawed. They consider saving one house in a town tormented by animate nightmares to be a success, and if the rest of the town fell, it is a tragedy, but to save the rest of the town means to die, rather than to live to fight another day.
This is what concerns me about Dark Sun, too. It doesn't really concern me about Planescape, because 4e isn't so much doing a "planescape setting" as they are using planescape elements in the default setting, which is fair enough.
But ultimately, I think different setting books, rather than just providing maps and menaces, should be providing me a way to play a character that is a different sort of hero, and to run a world that demands that kind of hero. Ravenloft heroes should not be the same thing as FR heroes.
