A recent podcast from Watch Out for Fireballs highlighted the classic adventure game Riven - the sequel to Myst. I loved the Myst 1-3. I went on to play some games of questionable quality (Darkfall, Frankenstein: Through the eyes of the Monster) because I enjoyed the genre so much. What I think hooked me was the alternate worlds and variety of puzzles. I especially enjoyed learning how a puzzle system worked in order to solve it.
Since that time, I have not played as many games in that style. The Room series was very good, but the Witness felt very repetitive and unsatisfying - I couldn't stick with it. I have Obduction on my list to play next, but I wanted to see if anyone had some hidden gems they would recommend. I've read though many "Greatest adventure games" lists, but those are pretty scattershot in recommendations.