Not to be missed!
You must complete your adventure through the Crystal Caves.
When you begin you will soon come to a giant gate which must be opened by using two switches. Open that first gate.
When you keep going, you will come to a place with a spiral pathway leading up, at its central point. You will get a projectile throwing power, and you must activate a switch by using it.
After passing through the first two gates, and further on when following the left path (it loops with the other path), a choir is sung at a place with several gargoyles there at. Throw a projectile on the exposed switch at the fountain in the center, then activate the other nearby switch, to expose another switch at the fountain and throw a projectile at it. Do this one more time, to reveal this secret.
The final area before the path out will be revealed, but is blocked by a coded door. You have to order your companion to stand on the pressure plate there at first, and then throw a projectile towards the switch on the left. Lastly, you must activate the other switch. All this must be done when the circulating dots are within the thinner area between lines.
Progress further on. Enter a room by a gate - this creates a Point Of No Return! Exit through the gate again, and step outside.
Then a beautiful video is played, followed by a stunningly beautiful loading screen! Accomplished!