ICO UNLOCKABLES
Lightsaber weapon
Finish the game once, then start another game. Follow the steps to where you got the Mace in the first time, and this time you will get a lightsaber that kills Smoke Creatures in one hit .You must be holding Yorda's hand to activate it.
Extra puzzle (PAL version)
An extra puzzle has been added in the room that leads to the top of the waterfall garden in the PAL version of the game. Whereas before you could shimmy around the room on bars, now you can only reach a switch. Pull this to start a giant wooden piston in the room. To get to the window, stand on the piston and press Jump just as it begins to sink to the lowest point. You should be catapulted up to a ledge. Just climb up to the window.
Two-player mode (PAL and Japanese NTSC versions)
Finish 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.