You begin the game on Myst Island, where you learn of a terrible event that has occurred.
Beginning the Game
After you watch the intro sequence, click the book, and click it again to open it. Or you can click at any time during the intro sequence to skip it. Then click the image on the page of the book.
The Message
Go forward until you reach a device with a lever. Flip the lever so it's pointing upward.
Go up the stairs, then go to the right and go up these stairs to reach a large cog wheel. Flip the lever so it's pointing upward.
Go back down the stairs, then go straight ahead to reach a set of stairs going up to the right. Go up those stairs, then click the piece of paper on the ground for a clue about a hidden message.
There is a third Marker Switch up ahead, next to a building with a gold emblem on the door, so go up to it and flip it upward like the other two.
Then turn around and follow the path to the right. Go past the building, and follow the path to the right, where there is a rocket ship. Flip the fourth Marker Switch to point upward.
Go back the way you came, and go to the right from the building, and walk toward the fountain, where there is a fifth Marker Switch. Flip it upward like the rest.
Go forward and you will see a brick building to the right. Approach it and flip the sixth Marker Switch.
Turn left, and go toward the clock tower. You can't reach it, but you can see the seventh Marker Switch there.
Turn around, and look for the cabin in the forest to the right. You find an eighth Marker Switch there. Flip it upward.
That is the last one, so now you have the code to see the message that was mentioned on the piece of paper that you found. Go back to the dock where you started. At the far end, there is an angled door in the wall. Click it to open it, then go forward until you reach the fountain. Turn around, and click the note on the left wall. Click the button on the upper-left of the panel, then click the arrows to make the numbers say 08. Then click the red button. Afterward, turn around, then click the button on the front of the fountain.
The message mentions using tower rotation to get the access keys.
The Library
The next place to explore is the library, which is the large square building with columns. Go inside.
There is a bookshelf facing the entrance of the library. Most of the books have been burned and are unreadable, but there are several that can be read. You can read them to learn more about the story of this world, as well as find some clues that you will need later.
The Red and Blue Books
On either side of the library is a red book and a blue book. You can click the red page next to the red book to pick it up, then click the red book to put the red page into it. Then open the book, and you will meet Sirrus. He asks you to bring him red pages.
You can do the same with the blue book on the other side of the library. By doing so, you will meet Achenar, who asks you to bring blue pages.
Tower Rotation
There is a painting on the library wall of Myst Island. Look at it and you will see outlines of the various buildings on the island, if you have flipped the Marker Switches as described earlier. (If you didn't flip all the accessible switches, you should go do that now.) If you click and hold the blinking circle, you will rotate the tower. Rotate it until the line from it turns red.
The places where the line turns red are the cogwheel, the sunken ship, the tall tree, and the spaceship.