I'm on a trip and playing this in my van at night. It's really nice to feel like this micro genre is still alive. I'm stuck and I like that? :)
My first experience was watching an older person play through Shadowgate at a house party. I was just a kid but others sat around and watch the guy go through it. We were all captivated. I loved the cryptic puzzles, creepy isolated vibe, and how the castle became deeper and more mysterious. *spoiler* In Infested, I was just killed by the pilot and didn't see it coming. That is also a major element I think you nailed.