Generally speaking the more horror you consume the more jaded you become and the more intense an experience it takes to get a reaction out of you. How unsettling a given game is largely depends on the purpose. If your new to some of this stuff, I can see how some of the more "Tame" games can seem fairly intense.
Truthfully I think they need to make more games for the Jaded horror fan, crank that M rating up to the maxx. If the ESRB isn't throwing a fit, you aren't doing it right.
Overall I tend to rate the "Fatal Frame" series as the best overall, I HAD the whole trilogy but misplaced the second game somewhere, and it was arguably the strongest installment. :/
Silent Hill is a mixed bag for the most part, a lot of people like the first two primarily, me I think the most atmospheric one is the fourth one hardly anyone likes (The Room).
Resident Evil is "horror" in the sense most zombie movies are. Meaning it blurs the line between action adventure and "horror". When it first came out however, there was nothing like it. Honestly though the best "Zombie" game is probably actually Dead Rising despite some really annoying design desicians (such as a draconian time limit).
It would be nice if I could find another Rom/copy but perhaps the first horror console game was "Sweet Home" for the SNES. Never released in the US to my knowlege, a computer or so ago I actually had a translated fan-to-fan version of it.
I consider the first real "Survival Horror" game to be "The Legacy" for the PC, alas I've never gotten Dosbox to run so I could play it again, but frankly if any horror game needs to be remade for modern audiences it's "The Legacy". I used to have the special edition I picked up from Radio Shack.
