I never really had a feeling of horror. But I get your point, you say that we fear the unknown, but once we start learning things that fear disappears. But isn't that unavoidable?That's not completely true. We have learned a lot about the subnet through the games each game reveals something new. What sublevel meant was this: with each new revelation the sort of urgent, "Where the hell am I!? I want to get out of here!" feeling dampens. In the sub2 thread I said that as we move along the series the feeling of horror is replaced by curiousity.
Also, what I meant is that the Sub8 plot (especially the secrets) left us with much more questions than answers. Wouldn't that count against the feeling you are describing?