Each world, known as an Age, was once used by the D'ni in their great empire. However, through a series of events, the culture violently collapsed during civil war. Now their home, the great cavern below the Earth's crust, lies dormant. While the original Myst games explore the lives of the few surviving people with the ability to Write, Myst Online documents humanity finding the lost D'ni civilization and their reconstruction of the cavern through the D'ni Reclamation Council.
Some other players may approach you and say, "Shorah." Shorah is D'ni for "peace" and is a common way of saying hello and goodbye in the game. D'ni actually has a fully formed language for those willing to learn it, so don't be surprised if players speak or type in a wispy, elegant language that sounds unfamiliar.
Starting out in the game
Starting with Myst Online is actually, quite easy. Yet, to a newcomer, the options presented from the beginning of the game can be a little daunting.
Upon logging in, you will be in Relto, your home age. Think of Relto like your own personal house. You'll store all of your linking books here in your library, you can track your progress in the game, and you can customize it by finding pages for your Relto book in all of the ages. So keep your eye out for small slips of paper!
Once in relto, you'll have two options -- either explore "The Cleft" and learn the general gist of the game through playing a simple age, or dive into the online world by accessing the Neighborhood (aka, Bevin) book in your library.
To acquire your in-game HUD, the KI, you'll need to go to Bevin. The KI handles basic functions, like screenshots and your friends list, but it also has advanced features like creating markers and handling map coordinates from the Great Zero. Once in Bevin, go to your left and find the Bevin library -- it will be up the steps and will have a balcony with stained glass windows. Inside of the library, find the book that sits under the stained glass window that has a giant fortress. (See the picture to the right for a screenshot.) The book will have an image of a tough, concrete structure inside of it -- that's what you want.
Once there, literally follow the signs and go through the open doors until you find a imposing machine. Click it to insert your hand into it, and the machine will wrap a KI around your palm. Congratulations! You have your HUD!
A few final words
The community of Myst is what makes the game great and keeps the game alive. They are a very active, very close, and very fun community that's worth interacting with. While you can certainly "solo" the game, make sure to meet other people, visit the larger areas of the cavern like Ae'gura, and participate in the game. If you have questions, ask those around you. Many people will be more than happy to help without spoiling the experience.
If you have time, be sure to check out the many notebooks lying around the cavern. They contain notes from the D'ni Restoration Council, and you can sometimes find hints and clues about puzzles or learn more about the deep, deep lore behind the game.
If you're confused as to where to go to get to somewhere else, check out the Guild of Greeters's map of the ages.
And that's it! While this isn't a comprehensive guide to everything in Myst Online, it should be enough to get your feet wet and acclimated to exploring the many ages. If you need some more guidance, check out this great beginners guide from, once again, the Guild of Greeters. There isn't a single right path to playing the game, so be sure to go wherever your feet take you. Safe travels. Shorah b'shehm.