I finally dove into "Nightmare" after slowly wearing down my ingrained "don't get killed; you only have so many lives" conditioning from previous games over the years.
It was...a blast!
Liberating, actually, [/size]since I found I wasn't so worried about the dying. But scary. A[/size]s you mentioned, the alien's heightened awareness and the unreliable gameplay aids made the frights all the fresher.
I actually started another "Nightmare" session with the mission of getting all of the tags, Nostromo logs, and other "finds", but never finished.
I really enjoy this game and hope to revisit it soon. I play it on a 55-inch LED TV. The wife enjoys watching me play since she's a fan of the film too. Great game; great gal!