High-Definition Mode
To run the game in "high-definition mode," turn on the PS2 and immediately press and hold the following buttons at the same time: "L1," "L2," "L3," "Square" and "Circle." For this cheat to work correctly, you must press the buttons before the screen reading "Sony Computer Entertainment" appears. If you're successful, the letters will turn purple when this screen appears.
Completion Unlocks
Many of the cheats in "God of War 2" are unlocked by completing the game. Upon defeating Zeus, thus bringing the story to a close, you will unlock alternate costumes one and two, the "hydra" armor, the seven-room mini-game "Challenge of the Titans" and the "Titan" difficulty setting. While it doesn't matter what difficulty level you beat the game on for these cheats, to unlock costume three, you must beat the game on "God" difficulty. For costumes four and five, as well as the "Athena" armor, you have to complete the game on "Titan" difficulty. This will also unlock "Hercules" as a playable character.
Challenge Mode
After unlocking and playing through the "Challenge of the Titans" mode, you will be ranked according to your performance. To unlock the "Arena of the Fates," you must earn the rank of "Titan." Earning a rank of "Mortal" will unlock the "Urn of the Fates," which can be equipped to extend the time of your combo meter, allowing for higher combos. Completing challenge mode with a ranking of "Spartan" will unlock the "Urn Of Poseidon," which is allows you to use the special attack "Poseidon's Rage." And to unlock the seventh alternate costume, beat "Challenge of the Titans" with a ranking of "God."
Gifts
There are two hidden gifts in the main story mode that will increase your health and magic abilities. To find the "Gift of Health," go to the area where the second translator jumps to his death. If you place the fate statue at the end of the hall by the gate, you can go through the adjacent mirror and freeze time. Go back to the original place of the statue and open the chest that has appeared. For the "Gift of Magic," go to the part of the game where you must climb the rope suspended over the lava flow. This is right before the moment when you have to burn the feathers of the phoenix. When you have to jump over the lava, instead of flying, equip your bow and arrow and shoot the wall below you to open a secret compartment. Land inside and open the chest.