Successfully complete the game on any difficulty to unlock the Temple Of Zeus.

Successfully complete the game on any difficulty to unlock the God difficulty.

Successfully complete the indicated task to find the corresponding item. Note: The items can only be used after completing the game.

Aphrodite's Ambrosia (Might Of Sparta attack): Successfully complete the sex mini-game in Sparta three times.
Athena's Owl (finds treasures).: After Kratos destroys the Athena statue in a cutscene, search the pile of debris on the right side.
Bonds of Ares (infinite magic): Enter the Domain of Death through the Death Gate in Atlantis, and look in the southern area.
Callisto's Armlet (win context sensitive mini-games): Immediately after defeating Callisto, search the ground near the battle.
Grave Digger's Shovel (play as Zeus in Combat Arena): Unlock everything in the Temple Of Zeus, and then follow the path that opens.
King's Ring (collect 10x the amount of red orbs): After King Midas turns the lava into gold, drop down by the area where he touched it.

Successfully complete the indicated task to unlock the corresponding costume:

Deimos: Successfully complete the game on the Spartan difficulty.
God Armor: Successfully complete the game on the Spartan difficulty.
Ghost Of Sparta: Successfully complete the game on the God difficulty.
Grave Digger/Zeus: Unlock all other bonuses at the Temple Of Zeus, solve the puzzle, and use the shovel. Note: It is only usable in the Combat Arena.
Legionnaire: Enter unique code provided as pre-order bonus.
Robotos: Purchase from the Temple Of Zeus for 250,000 orbs.

Go to the Combat Arena, and set your health and magic to "infinite". Select the Easy difficulty and any desired enemies (Cyclops Tyrant and the Minotaurs are recommended) in the largest number possible. Use the "Scourge Of Erinys" power (at maximum, if possible). Since you have unlimited magic and health, just repeatedly press Left to get easy orbs. -From: Wendelle