I'm sure people will remember the old point and clicks, where you are expected to fail, both to pad out play time, and to push strategy guide sales, back before you could just look up a walkthrough.
There's the old-OLD Sierra games, the Lucasarts games, and in my favourite, the Horrorsoft ones. All horror themed, obviously, with some of the best music and visuals I've ever seen. Especially Waxworks, though the Elvira games are incredible, if basically impossible without guides.
Wbu, you hold any dear? Still play some to this day? Never finished myst?