Hint: Destroying the Smoke Creatures easily:
If you enter a room, and it is a clear run to the portal on the other side, take Yorda by the hand and run her to the portal with the black Smoke Creatures chasing you. As you approach the portal, Yorda's activation of the portal will create lightning which will destroy the creatures anywhere near you.
Hint: Finding Yorda:
When in the last level with Ico's horns cut off on the beach, go towards the left following the shore of the beach to find Yorda.
Hint: Avoid losing Yorda:
To avoid losing Yorda, as soon as you set her free press R1 and hold her hand, then run to the door . You should also pick up the stick that falls so you can defeat the Shadow Creatures easily.
Hint: Turning wheels:
When turning big wheels, as when shutting off the water, turn from the farthest point to go faster.
Hint: New weapon:
After reaching the top of the waterfall area, to the left of the switch you pulled is a tall tree. Swipe at it with your sword until you make contact. A ball will fall from its branches. Take the ball up the stairs, into the opened room, and drop it. You will notice tree arches between the two stairs going to the upper level of the room. Go to the middle arch and push on one side of it to make it revolve and reveal a secret room. Go back and take the ball (and Yorda) and enter the secret room . Hop into the idol pedestal with Yorda and a basket will appear. Take the ball and shoot it into the basket. A mace will fly through the window. It is more powerful then the sword and the 2x4. You can take out a standard Ghout in three swings.
Two-player mode (Japanese version):
Successfully complete the game and wait for the credits to end. Once you regain control of Ico, look for Yorda near the seashore. A save prompt will appear after the final ending. Save the game and restart to have Yorda playable using controller two and new music.