I have to completely disagree with the video. Amnesia would not be less scary if it had higher resolution textures, better shaders and higher polygon environments. Amnesia is scary because it gets the pacing right as well as it effectively employs core horror elements. These elements are isolation, hostility and vulnerability, tension and the unknown, urgency and despair, the illogical or impossible, expectation and anticipation, and hope. These elements in the context of Amnesia are expressed as:
1. Isolation: the player is trapped in a keep with no one to turn to or depend on. Most horror stories involve physically isolating the protagonist. Mental isolation is more difficult to convey but can be just as frightening if not more so. There may be people with you but your way of thinking and seeing things perplexes or agitates them, making them incapable or unwilling to understand or help you.
2. Hostility and vulnerability: the player is in a dangerous environment that physically and psychologically threatens him. Worst of all, he does not have the strength or the means to successfully combat this threat.
3. Tension and the unknown: Tension is always tied to not knowing. Long-term tension is brought about by trying to find out why you lost your memory, who or what is out to get you and why, how did you get trapped here, and how will you make it out alive. Short-term tension is produced by not knowing if your limited resources will last, what is creating those strange footsteps and growling noises you just heard, and what cast that odd shadow you just saw move in the corner of your eye.
Even in normal, day-to-day activities, tension is derived from not knowing. You are tense about a performance because you do not know if it will be received well, you are tense about an interview because you do not know if you are qualified, you are tense about a date because you do not know if you will make the right impression.
Tension is the most important element in horror. Keep the player or viewer guessing. Set up expectations and then don?t deliver. Ask questions but don't answer them. Then pace the tension with brief moments of respite or enlightenment that invariably lead to more questions and expectations. In Amnesia there is a letter you wrote to yourself that asks you to kill someone. You have no idea who this person is and why you should kill him. Eventually you find out who he is and what he did. This revelation answers those two questions but it now forces the player to ask why this person did what he did and can this conflict be resolved in any way but murder.
4. Urgency and despair: the player is reluctantly forced into action. If he sits still the lamp oil runs out, his sanity drops and his persecutors get closer. However, his actions bring about despair. Every step he takes and every piece of the puzzle uncovered seems to bring him closer to the very thing he is trying to get away from. Every action takes him opposite the intended direction but he is pressured into acting by forces beyond his control.
5. The impossible: we like living in a world that makes sense and fits into our understanding of reality. Disturb that and the mind has a hard time coping. The supernatural elements that haunt the keep are just that: supernatural and impossible. Admittedly, the occult is one of the easiest and most universally accepted ways of conveying an impossible reality. Unfortunately, its pervasiveness makes it alone an ineffective way of depicting horror.
6. Hope: despite the overwhelming and unknown odds, there is a tiny bit of hope that with enough luck, caution, and perseverance, the player just might solve the mystery and make it out alive.
Note how none of these elements are tied to any visuals. Visual elements can be used to help convey some of these concepts but it is how they are used that makes them effective, not the medium in which they are defined. (high poly vs. low poly, text vs. film, etc.)
I loved Dead Space but it did not deliver well on some of these principles. It relied too much on frequently startling the player (even pacing). Many "scary" areas or events were obvious due to recurring patterns (met expectations). The player eventually grew too powerful, making you feel competent enough to take on the enemies head on(lack of vulnerability). The threat was too well defined, allowing you to logically interpret and asses the danger around you (understanding).
If it were up to me, I'd make the monsters in Dead Space invulnerable. You can incapacitate them to the point where they can do little more than inch very slowly towards you but you can't kill them. With a bit of care, you can easily circumvent them once they reach this state but, as you travel deeper and deeper into the ship, in the back of your head you know there are literally dozens upon dozens of relentless, mutilated monstrosities inching their way closer you so you'd best keep moving. Instead, once I "clear" an area I know it's safe and I can just chill out and look for hidden loot, only moving on to the next area and new dangers on my own terms.
Going back to the first point (isolation), I can't help but bring up Alice: Madness Returns. The game itself is not horror, just visually creative and stylized, but I think it does a fantastic job of visually portraying isolation in a world filled with people. In the opening sequence you play as Alice prior to entering wonderland. Alice is rendered as a beautiful, young female yet every single person, young or old, male or female looks off and twisted. Sometimes I think they are not really twisted, but Alice perceives them that way because of her trauma. Regardless of the reason, you can immediately tell she is not one of them and is alone in the world.
The fact is that a truly scary story, movie or game takes a great deal of planning and careful execution outside of the visual and aural. I'm not surprised that these elements are better expressed in a labor of love, like Amnesia, than in a AAA conservative title like Dead Space. There is no reason why Dead Space, with its high production values and huge marketing campaign, could not have been as scary or scarier than Amnesia.