Obsidian senior designer Chris Avellone posted a new developer blog update discussing the recently PC and PS3-released Dead Money DLC for Fallout: New Vegas, specifically its design intentions.
Regardless, we were shooting for a Horror experience with Dead Money. As for what we tried to do with Horror, to make the game scary, we tried to do two things - one, have enemies you couldn't headshot and required a different approach (holograms, toxic cloud), and worse, they could headshot you if you weren't careful (bomb collars + radios). My experience with most horror games is that the enemies become scarier when you can't kill the adversaries (which most role-players will try and do if the enemy has any number of hit points or any measurable way to hurt them, no matter how small). So what am I happy about, even if the final result ended up veering from the intention, is watching YouTube playthrough videos where folks (1) start panicking when they hear beeping (exactly the experience we wanted), and (2) seeing players take a step back, figure out the puzzle, and then study the environment to solve it (again, what we wanted).
As for Horror: Things get scarier and tense when you can't escape, no one's coming to help you, and your resources are limited, and Dead Money was built around this. Watching the YouTube playthrough footage where players started re-appreciating chems and Stimpaks made me happy - these things are miracles of medicine, and they should be viewed as such and appreciated for that in the world of Fallout. One issue I've always had with Fallout is it's really easy to amass a lot of chems and stims, so much so you lose the sense of wonder and relief when you get these items, and I feel situations like in Dead Money can give you a new appreciation for food, crafting (we put a higher priority on crafting and supplies to make crafting worth more in the DLC), unconventional water sources, and the joy at finding an otherwise common chem in the Mojave takes on a new level of preciousness when you're in hostile territory. One YouTube video showed someone finding Buffout - and to hear them say, "thank god" and hear genuine appreciation for finding something so rare is exactly the kind of value I want people to attach to these items... usually people seem to care less when they find Buffout, but it all depends on the environment context. I want players to attach value to them again rather than, "oh, more Buffout." It's BUFFOUT. It's a STIMPAK. Your character should be OVERJOYED to find these things, each and every time.