I found this comment string from Rand intereresting:
"I think after doing both Myst and Riven we came to realize that the compartmentalized puzzle solving of Myst’s distinct ages was a good thing. ... In Myst when an Age was completed there was a huge benefit to being able to mentally check it off the list. Riven mixed up the “Ages” in small, but irritating, ways - because once you realize that you require something from another “Age” the nice security of the boundaries goes out the window."
MYST was most definitely not "compartmentalized". If you played MYST, what age did you go to first? EVERYONE went to that Spaceship. Right? And the final underground sub maze needed what info to complete? Info found in the Mechanical age.
I spent hours in that thing, frustrated, until I looked at the guide book (online free walkthroughs not available yet) to discover the solving "secret".
I think there might be other crossovers, but I can't think of them right now. Doesn't matter, no game, for me, will EVER be greater than MYST. Though...........Half Life 2 comes close (see my posts in the Darkside).