I'm glad someone mentioned Stephen King.

The reason people get so enthralled with his books and are so horrified by the gruesome parts and psychological terror is that he spends 90% of the book giving the characters lots of back story.

He wants you to empathise with them, understand them and perceive them as real people with personalities... Before he brutally rips that away. That way the effect is so much more blunt and it hammers the point home.

Another place you can see this used is the walking dead TV series.

There are several games that have the same ace in their hand, for example last of us, or the actual walking dead games (the telltale ones, not that God awful fps one) and silent hill 2.

In short make your player care about your characters, especially if you're going to hurt them.

Hope this helps!

Sufficient constant surprises (to the point you are wary every step you take)

A way to handle them when they are something you havent seen before (different solution with the resources player has)

being able to amend your mistakes/failures

Fast and slow pacing (sometimes you would have more time to think and other times it developes too fast and you are in a panic)

Require different solutions - the game shouldnt be a shooting gallery with the same gun/attack being teh answer

Complications - where suddenly that nice weapon you depend on breaks/misfires

Things not being what you thought them to be (more surprise and uncertainty) - NPCs 'allies' who suddenly arent allies any longer

Suspence - Strange noises that you hear from a distance - somewhere is that thing you've already learned to dread encountering , but you dont know if its behind that next door

Other strange noises you suddenly hear, but dont know what they are (and maybe many you never find out)

Replayability - dont make it predictable on replay -- randomiize resources, spawn locations, spawn content, terrain, order of terrain traversal, attributes/abilities of opponents/hazards, etc... .

Have elements that are optional (different subsetsfrom a large pool ) on different playthroughs

darkness that hides who nows what (and not something you just crank up the brightness til you see everything)

Probably some would disagree with me - but I suppose that the most important part of the survival horror game is sound design and music.

I suppose that the most important part of the survival horror game is sound design and music

I would say you are very close to the more abstract layer. The MOST Important part is how the creator invokes the feeling of fear and horror. If this is done by amazing music or timed FX than yes I would agree with you. However, it could be done thru a well written narrative. So while sound is a great way to get the correct emotional direction it isn't the only.