Beat the game to unlock Hard Difficulty and Time Attack modes.
Look around for fruit trees or get the Fruit Tree Map (see below). When you see one, shoot down a fruit with your bow. Eat it to raise your maximum health.
Find and kill white-tailed lizards and eat their tails to increase your strength. The Lizard Detection Stone (see below), makes this much easier.
After beating a decent number of colossi (10 or so), birds will appear around the main temple. Jump at them and hold R1 to grab them.
Normal Time Attack Bonus items. You'll receive them for every 2 Colossi defeated, in this order:
|Whistling Arrow||Distracts a Colossus|
|Cloak of Force||Sword damages a Colossus more|
|Mask of Strength||Inflict greater wounds to a Colossus|
|Lizard Detection Stone||Detects white-tailed lizards|
|Fruit Tree Map||Reveals the fruit trees on map|
|Mask of Power||Inflict greater wounds to a Colossus|
|Cloak of Deception||Invisible to a Colossus|
|Flash Arrow||Explodes when hits Colossus|
Hard Time Attack Bonus items. You'll receive them for every 2 Colossi defeated, in this order:
|Harpoon Of Thunder|
|Sword Of The Sun|
|Fruit Tree Map|
|Lizard Detection Stone|
|Cloth Of Desperation|
|Queen's Sword From Ico|
Collect all items in normal Time Attack mode. At the title screen, hold Square to turn your horse brown.
Collect all items in hard Time Attack mode. At the title screen, hold Circle to turn your horse white.
If you have a savegame from the original ICO on your memory card, Agro will have the logo on his head instead of the normal one.
Secret Garden/17th Colossus:
Beat the game on all four modes (normal/hard & game/time attack). Then climb the outside of the temple to the secret garden at the ends of the world. The 17th colossus will appear in a short cutscene like the others, busting through the rear wall. After you fight him, the path to the very top of the temple will be opened, leading to a surprise.
Each individual Colossus can be found at the following map coordinates:
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