Since
Myst has been around for quite some time, most gamers could probably tell you what they believe
Myst is about. However, seeing as how this game is remarkably huge it's unlikely that any one player could tell you the same thing.
Myst is an incredibly shadowed game, with an unlimited number of possibilities in direction and plot advancement. One player could get a completely different game out of the same CD. The ability for the game to take different paths while still outlining the same basic concept is truly amazing.
There really is not much that can be said about Myst and its successors without giving away something. Just know that for most of the games, you are completely clueless. Actually, your avatar begins, in most cases, having no idea where he is, what he is doing, or even how he got to his present state. As the games progress, things start clearing up, and by the end of the game you think you have it all figured out, when some unbelievable trick is thrown in front of you, changing the path of the game entirely.
You will have to figure out many puzzles along the way. Puzzles consist of various types, such as finding the padlock combination, aligning a celestial globe or just figuring out exactly where you are.
Each game builds upon the previous, but since the character is pretty much clueless throughout each game anyway, you do not need to play the three titles in order, although surely that is why you are purchasing a trilogy boxed set.