Are you talking what the physical problem is, or what caused it in the first place? What's the play style you're thinking of (top view, 3rd person, first person)?
Fear is caused by tension. I almost sounds like you are trying to cause fear by the tension of the player not knowing if something will or won't jump out at him. If nothing does often enough, that might get boring...
Which is why it might be difficult to pull of, the right balance of not enough and too much. My personal take on this idea would be to have depending on the size 5 distinctly different enemies patrolling it, none of them are confined to a set zone and each one would be difficult to kill/spot for different reasons if they meet each other they fight and you can hear it and if your quite enough even sneak in and watch letting you get a look at them, of course make too much noise or what not and they will both go after you. Various different things can attract them some avoidable some not but none would guarantee they come (Think panic and cresendo events in l4d only no guaranteed horde.)
As for enemies I'm thinking:
Stalker type enemy, super fast wall climbing most of the time, dark coloured so he hides well in some areas although well lit areas will screw him over, he's also almost blind so standing still will cause him to start searching you out with other senses, maybe if he can't find you he gives up and moves on. Has the best hearing of all of them so if you make a lot of noise he is most likely to check it out.
Shape shifter, can be anything it sees, intelligent enough to eat things before shifting so you wont spot it through double items normally becomes you to attack head on but will prefer to wait until you get close enough then shift into something like a snake and try to crush you.
Tank type enemy, big strong and nigh indestructible but stupid and has poor senses so unless you make a ton of noise you wont attract it, it also makes a lot of noise so your normal tactic when it comes along should be to run and hide.
Sentient gas. This is just what it says on the tin a cloud of hallucinogenic gas which can think, these will be generated by another enemy somewhere so they could be classified as a weapon rather than an enemy, the enemy that spawns them would be slow moving and unable to attack in it's own right, the gas would travel through vents at a speed a little above yours, although it would have trouble with corners (queue dramatic chase scene) it dissipates naturally and if you breathe it in, of course if you do that you'll start seeing all kinds of whacky things and likely make a lot of noise, not a danger on it's own but likely to bring it.
Ok I can't think up any more right now. The station would be large and decorated as if it was somewhere you might actually you know live. There would be absolutely no flickering lights and very little of what you might consider the traditional horror fare, instead it would be set somewhere eeirly similar to someone's house, you know the type you would be in while playing.
Infact I quite like this idea I'm with Jakkarra if you're serious and you'll have me (I have no experience so maybe I shouldn't be taking on a big project like this but I'm eager and have absolutely nothing else to do.)