Complete the game to unlock the following:
Fear Kratos costume (Wearing this costume allows you and your enemies to do quadruple damage.)
Challenges Of Olympus
To unlock the Combat Arena, complete all challenges.
Godly Possession locations:
Collect the following Godly Possessions to unlock the corresponding effect after the game has been completed. The Godly Possessions must be equipped in the "Items" menu for their effect to become active:
GODLY POSSESSION - LOCATION
Zeus' Eagle - Unlimited Rage of Sparta.
Hades' Helm - Maximum Health, Magic, and Item meters.
Helios' Shield - Triple the Hits counter.
Hermes' Coin - Collect ten times the amount of Red Orbs.
Hercules' Shoulder Guard - Decrease damage taken by 33%.
Poseidon's Conch Shell - Unlimited Magic.
Aphrodite's Garter - Continue to use Athena's Blades.
Hephaestus' Ring - Automatically win all context sensitive attacks.
Daedalus' Schematics - Unlimited Item meter.
Hera's Chalice - Health meter slowly drains over time, but never completely emptying it.
Extra Red Orbs:
When fighting those sword-wielding Olympian skeletons, kill some so that there about ten left and position Kratos with his back to to a wall. Equip the Claws of Hades (which need to be at level 2 or higher). Repeatedly lash out with the Soul Rip (L1 + CIRCLE) and you'll get hundreds, even over a thousand hits on just a few enemies. The Soul Rip attack deals very little damage. On hard modes you can probably increase the hit count further and be rewarded with more red orbs. Note: If you don't back against a wall you'll have to move towards enemies a bit after each attack.
Mysterious Website for Platinum Spartans:
If you get the Platinum Trophy in God of War III you'll be directed to the following website featuring only a compass and falling rain:
New Game+ glitch:
There is no New Game+ option but you can do a glitch that gives you maxed out weapons and infinite magic at the starrt of the game. First you must unlock the Combat Arena. Set magic to infinite. Get killed in the Combat Arena 5 times so that the game asks if you want to switch to easy mode. Choose no. You should be at the main menu now. Start a new game on whatever difficulty you were on during the Combat Arena. You will begin the game with all weapons maxed out and infinite magic.
Max weapons glitch:
Complete all Challenges of Olympus to unlock the Combat Arena. Start the Arena on Titan difficulty and die a couple times. When the game asks if you'd like to switch difficulties, choose "No." Quit out and start a new game and you'll have all your weapons maxed out -- even in Chaos Mode.
Note: Equipping a Godly Possession item or the Fear Kratos costume will prevent trophies from becoming unlocked.
Mr. Hand - Discover the secret 'Hades Room'.
Hit Man - Perform a 1000-hit combo.
Rip One! - Rip apart 1 Olympus Sentry.
Nice Tan - Blind 100 enemies with the Head of Helios.
Obedience School - Deliver 50 kicks to Hounds.
It's getting hot in here... - Burn 100 enemies with the Bow of Apollo.
Souled Out - Summon every Soul with the Claws of Hades.
Bloody Hell - Cover Kratos in 500 buckets of blood by killing the enemies.
No Guts, No Glory - Gut 3 Centaur Generals.
Hitting Your Stride - Upgrade any weapon to the next level.
Ladies Man - Successfully entertain Aphrodite.
Releasing the Flood Gates - Kill Poseidon.
Burnt to a Crisp - Acquire the Bow of Apollo.
Mr. Hand - Discover the secret Hades Arm room.
Shine Lord - Kill Helios.
Shoe Delivery - Kill Hermes and acquire his boots.
I didn't do it... But I wish I did! - Kill the Poseidon Princess.
Handy Man - Sever Gia's hand.
Open Sesame - Open the Gates of Tisiphone.
Rescue Me - Save Pandora.
Three Wise Men - Solve the Puzzle of the Three Judges.
Eye Candy - Collect all of the Gorgon Eyes.
Feather Plucker - Collect all of the Phoenix Feathers.
Are You Horny to Win? - Collect all of the Minotaur Horns.
Maxed Out! - Completely upgrade all the weapons.
Hooker - Kill Hades.
Titan Slayer - Kill Cronos.
Sibling Rivalry - Kill Hercules.
Retribution - Kill Zeus.
Freezer Burn - Acquire the Boreas Icestorm.
Seeing Things From a Different Perspective - Solve Hera's Gardens.
Vengeance Complete - Beat the game.
Up to the Challenge - Beat the Challenge of Olympus.
Unhuman - Beat Titan Mode.
Priceless - Collect all of the 'Godly Possessions'.
aMAZEd - Beat the Labyrinth Without Dying or Failing.
King of the Hill - Earn all Bronze, Silver, and Gold trophies.