What do you think the degree of difficulty and length of play each Myst series game has?
I believe Myst lasted the longest, since I played it when it came out and the concept was so new. Then Riven, because it had so many islands. IMO Riven is the greatest because it had frightening elements and a real sense of dread. But Exile's wonderful ambience and music may be my secret favorite because I like to go back to it "for a vacation!"