Wait, was Myst in hypercard? I remember watching videos where they talked about how everything was only in 256 colors with adaptive pallets, plus they had Windows, 3DO and Plyastation ports.
It definitely was written in HyperCard, using a couple of custom 'XCMD' extensions for the color images and QuickTime animations, which HyperCard itself did not support at the time.
One of my early contract jobs involved reverse-engineering the entire game and reconstructing it as a screen-saver, with a little AI that would generate plausible game-play activity while you watched. The startup that hired me got sued out of existence approximately ten seconds after shipping the product, despite our scrupulous attention to copyright (everything we used was loaded off the CD at runtime), and that was a valuable lesson about the true nature of the legal system. Even still, the experience of immersing myself in that game world deeply enough to recreate its structure remains a fond memory.
The Mac version was in Hypercard, all of the other versions were different engines written from scratch for Myst.
They actually had to use the same color palette for each age to ensure there wasn't any strangeness as they flipped between cards to move around in the game.