I also love the Myst series, especially Riven and Revelation. They both have a space on my top 3 list.
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Also I'm curious as to why people feel that the Myst games are so hard? I didn't have nearly as much trouble with it as with for example Sam and Max, Day of the Tentacle, Discworld, ...
Most of the puzzles in the Myst series are all quite logical and solveable if you just pay attention to details... If you want difficult, then try out the DVD version of Schizm...