Having read all that, there's nothing specific I need to reply to, so here's my unsolicited view:
In Overture, the first dog scared the pants off me.
Completely and utterly panicked me. I was, admittedly, playing alone, in the dark and at around midnight.
(Never again ... oh sweet lord no)
I was literally terrified.
The Tuurngait in Black Plague never once stopped petrifying me.
That part in the facility with the key and the running around with them chasing you? Not once did that stop scaring me. Not once.
Yeah, I realised that I could just about stay ahead of them if I sprinted, but the fact that you have to face forwards and just *hope* that you can continue to outrun them, that had me on the edge of my chair every second.
I loved it. Oh, sure, I hated it like nothing else, but I loved it too.
Monsters *are* scary. Terrifying, in fact.
But only so long as you can't hurt them.
Bad guys are not scary. Not for a minute.
That feeling of sheer panic when the first Tuurngait in Black Blague busts the door open and mashes you into a pulp in the corner while you cannot do a thing? Sheer terror.
And personally, I didn't feel that let up, and I think those two games are easily the most immersive, and impressive I've seen in a long time.
Most immersive ever, in fact, and most impressive since Portal <3
So yeah, maybe Requiem was just a puzzle game that was only scary because of the "Penumbra" tacked onto the beginning of the name and the title music, but we'll let that one slide - it won't stop me from buying Amnesia, not for a second.
But while I'm ranting - please, please don't make another game that's too hard :-)
The main problem with Requiem personally was actually that it forced me to quit and come back to it lots of times because the puzzles/solutions weren't obvious.
The others I could just sit down and play through (pausing to let my nerves and sanity recover, naturally) but Requiem the puzzles were all it had, and they were too hard to be really fun.
You don't have to tax someone's problem-solving skills to the max to make them enjoy the game, there wasn't one bit of the first ones that made me think "But I've done everything I possibly can, and there's just no way through here" - the only thing stopping me was a genuine desire not to even *know* what was on the other side of that door, not that I couldn't open it :-)
[/rant]