Every now and then, I think it's fun to really bring some horror elements to a role-playing game. I don't think this is necessarily an easy thing to do. I mean, a lot of the mundane monsters in a fantasy RPG would seem rather scary to me - but they are so common and the heroes are...well, heroes. I think a lot of it comes to writing style and game design - if the adventure can hold back some mystery and grab the characters (literally) unexpectedly, then you got something.
One of the best D&D adventures I've run as a GM was Greg A. Vaughan's "Tammeraut's Fate" from Dungeon # 106. The author took a classic horror film idea - stranded on an island and under siege by zombies - and really made something that resonates.
It did not seem like a tired cliche or dull or anything less than a suspenseful series of scary encounters. It was kind of fun to do a little give and take on pushing the adventure - the player characters need to drive a bit, otherwise they rightly feel that they are only reacting to situations - BUT - I think they got a kick out of knowing that the situation was out of control while they investigated the island's hermitage. It was tense and they knew they were up against some dark forces even before the sea zombies showed up. As a GM, these are the kind of moments you work towards - when the players are scrambling, using desperate imagination and tactics to get their characters out the other side of the adventure.
This gem from 2004 can be found as a hard copy or PDF from Paizo here.
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