Things that would have made Amnesia scarier

[Culinus]

Would have been scarier if the water monsters show their forms out of the water when they attack you.

I really disagree with this. I think the scariest part is definitely the unknown, and the most memorable and enjoyable parts of the game was all the walking around expecting something horrifying to happen. Personally I didn't find being chased by monsters to be the most frightening, the anticipation was the worst (best) part.

And what I really love about the game design is how dumb / incompetent the monsters are. The fact that you can just about always escape from one (if playing properly) just makes you panic every time you bump in to one rather then just thinking "ooh well". And the hard part is of course to conduct any form of rational thinking when you're panicking and running for your life, and instead you end up trying to open the damn door 5-6 times unsuccessfully. Clearly it's not only the monster that's incompetent.

And to get back on topic of how to actually make it more scary; I'd say to work up a bit more to the moments when you're gonna face the monsters. Of course you can't do it every time since that will make people anticipate when they're gonna encounter one, but for example: Say that first you open a closet and something falls out towards you (skeleton, body... or something more normal), then you open a door and some form of a trap goes off just missing you. Then you proceed to open another door and you find a monster there facing away from you, doesn't actually notice you opening the door (this door could be silent for once). So by this time I'm guessing your heart would be racing, and you have to close the door silently, slamming it would make the monster aware of your presence and lunge at you.

Another thing that would have made an improvement on the game would have been to not actually have the monsters despawn. Or if it's a vital part of the level, have them at least reappear from time to time. I'm not 100% sure but it seemed like the monsters only patrolled a certain route in the instance and then despawned when it was done, or maybe he just completed the damn level before me every time

But again, the most frightening wasn't actually the monsters, it was the small things, like the paintings and the sounds from the torture chambers.