Gate Room Puzzle
To advance in "Riven," you eventually need to get into Gehn's world. To access this world, you must solve the Gate Room puzzle. When you start the puzzle, you will see a button in front of the gated room. Press this button four times. Turn left to go to the gate, and click it to maneuver your way under the gate. Move forward into the room, find the switch in the room, turn it on and turn around. Continue moving forward until you find a lever and a button. Pull the lever, and then press the button two times. Go forward to another passage, and do the same thing with the lever and button. Move forward again and press the button twice. Do not touch the lever. The gate will open, and you'll be able to enter the fire marble dome.
Sound Clues
Keep your speakers turned up throughout the game -- you never know when an area will give an important sound clue. For example, on Jungle Island, when you touch the wooden eyes, you hear a sound clue that will be important later on in the game. Touching the wooden eyes also reveals hidden symbols.
Jungle Secrets
When you get to Disc 3 of the game, you see a forest area with all the trees cut down. Move around until you find the path and a gate. Go through the gate and continue walking straight. Toward your left you'll see a large dagger on the ground. Walk down a slight hill, and you will eventually come across a rolling ball. Click the ball and memorize the symbols that appear and the sound it makes. Go back to the path and continue walking until you come across a fork in the road. Turn right and continue walking until you find a large fish head. Inspect it, but it will indicate nothing was found. Return to the path and find that two lamps have appeared. Walk toward them, and you will find one of them has a small disc on top. Inspect the disc, and something will happen.
Changing Discs
Throughout the game, you will have to change discs multiple times. Each time you change discs, you enter a different world in the game. To keep all the puzzles and things you've encountered straight, make sure to inspect everything thoroughly before changing discs and moving on to a different land. This will save you a lot of backtracking later on.