Imaculata
Hero
I think you can use pretty much any system for horror campaigns, including D&D. I think the trick is to simply remove a lot of combat from the campaign as a DM, or to make the monsters really strong.
Of course some rules systems are better suited for horror than others. Call of Cthulhu is a popular system for horror for example, and there's the recently released Alien roleplaying game I believe.
In the past I've used D20 Modern for a horror campaign, which is basically 3rd edition, but with a modern setting, which works just fine. Just keep combat and weapons to a minimum, and focus on atmosphere and feelings of dread. The downside is that with this sort of campaign, it is the story that needs to do a lot of the heavy lifting. So it helps if you're a good storyteller.
Of course some rules systems are better suited for horror than others. Call of Cthulhu is a popular system for horror for example, and there's the recently released Alien roleplaying game I believe.
In the past I've used D20 Modern for a horror campaign, which is basically 3rd edition, but with a modern setting, which works just fine. Just keep combat and weapons to a minimum, and focus on atmosphere and feelings of dread. The downside is that with this sort of campaign, it is the story that needs to do a lot of the heavy lifting. So it helps if you're a good storyteller.