-Detailed character creation, because its scarier when its you in the game and not some boring protagonist.
No it's not. Immersion comes from feeling like you are in a game, not when you think your watching something happening to you. The actual model has little to do with the experience. The most successful horror games have deep protagonists who hold a unique psychological makeup that is paralleled in the experience of the game. Having a boring blank slate of a character players can put themselves into will ruin the chance of doing this, unless the protagonist gets amnesia or psychological elements are determine through the actions of the player.
One possible exception to making the character model work is if the player could be transformed in the game, as people do have an innate fear of being turned into something else or having the wrong body. I never seen a fear game pull this off, but it could be more effective if the model was based on yourself. What's happening to my body? Heh, you could make a gender transformation horrifying if you do that right.
-Very little weaponry like bricks, household items and a flashlight, and make the flashlight actual take up a hand so in order to fight with both you'd have to drop it, makes for some pants sh*tt*ng fights when all you can see is the guys feet. Even give it batteries so you have to conserve light.
The point of a flashlight is to limit the players field of vision, because it is what they cannot see that truly terrifies them. I suppose you could have players be able to hit enemies with a flashlight, or make using the flashlight or any weapon attract more enemies to your location.
Often a field a vision can be limited by other factors, uncontrolled camera or first person views have built in limits. Poor visibility is also a popular notion, darkness, fog, pillars or trees blocking your view of a whole area, objects that look like enemies.
However, you cannot just limit players vision to scare them, you must also limit what they hear. The sound in the game should not make it clear when an enemy is there, but at the same time music and noises may be conditioned in a player to expect to come with an enemy some of the time. The scarcest sound of all of course is total silence, as you'd never expect to bump into an enemy when you don't hear anything.
-Healing like in Left4Dead, where you actually have to patch yourself up but this time don't include a completion bar, just leave us guessing if or when we've healed enough.
Nice idea, a lot of horror games do not have a clear life gauge, leaving players wondering how many more hits they can take and often causing them to use too many healing items. Of course, another big part to remember about horror is limited resources.
There should be few enough items and ammo that players feel like they might run out of their supplies. This also has the duel effect of making players want to explore every room for items, even if they really rather not explore in a particular area.
Think we got a good list of horror game tropes that work already, so the question is what phoebes would I like to see in a horror game?
Being followed is an obvious one, just telling the player there's something after him constantly tracking them down like a bloodhound will set this up. The only downfall is this doesn't give players the quite lull they need to get pulled into the atmosphere, rather it tightens tension. Ideally, this is something you want to be able to turn on and off, without making the player feel completely safe. Like making the player thinks they got away, for now.
Another common one is fear of the unknown, now you can make a monster odd and unexplainable, but what about making an enemy invisible. Maybe it can only survive is pitch darkness and you'll never quite get a clear enough glimpse of it. Or perhaps it is actually invisible and only seen through its interactions with other objects ?probably needs a good roar or grunt, to sell whatever it is. Whatever it is, seeing it should lead to death fast enough that you'll never get quite a good enough view of it.
For fear of heights you could teach a player that walking over a particular unsafe looking platform will result in you falling, first in an area where the fall won't kill you. The surprise fall the first time might be something on its own, but then later in the game when you're on a very high place, like say a skyscraper, force the player to walk across that same type of platform. Maybe showing the platform before hand, and then triggering a chase sequence where that platform becomes their only escape route.
Fear of discovery. While a lot of stealth game play isn't that scary, it could be if you're helpless enough if discovered. I even like the idea of "pretending to be the zombie" and having to walk along an area really slow so monster do not detect your not one of them, as your surrounded by them, with no weapons to defend yourself.
This brings me to another important one all my favorite horror games have, fear of being unprepared. At some point in the game, maybe once they player thinks he's strong, force the player to remove all of their equipment. No weapons, no flash light, no first aid, etc. Perhaps, using a built in excuse like not setting off a metal detector or it will exploded.