Another Muse Key
There is also a Muse Key behind the statue of Atlas in Pandora's Temple. In The Challenge of Atlas room, after you make atlas pick up "earth," if you walk around him to the left, there is a chest behind him. Open the chest, and you are given a muse key.

Bonus new game glitch
When you beat the game and start a new one you will probably notice the sword next to the mode you beat it in and if you start a new game and use the bonus play you will notice that if you are using the barbarian hammer while you are putting your godly power into the blade of Olympus(when you are pulling it out and it drains your health magic and exp)you will have to use the weapon selected thus meaning if you have the hammer while taking it out you will be stuck with it for EVA!

Easy gorgon eye
Ok right after you get done defeating madusa for the first time and get to the ladder,go up the ladder and you will pass a guy haniging on a pole(by the way if you jump back towards the guy there is a red orb box with a lot of orbs on it.)once you get up the ladder you will see a lever.but instead of using it go passed it and strait to the bow.use it to break through the wall and there will be a box containing a gorgons eye.

Infinite Ammunition
Pause the game and enter the following code: Select, Select, Circle, Circle, R1, R1, Start.

Infinite orbs
During the Challenge of Atlas after you cross the bridge and pass the saw room, there will be an enemy at the bottom of the tower. Don't kill him, just go to the ladder near the wall. Position yourself so that you are between the enemy and the ladder. Use the square, square, triangle combo to take him out. Make sure you kill the enemy above the ladder. Once you kill it, it should hit the ground, then bounce back up getting caught in this bounce. If done correctly, it will continually release red orbs. Once you get the glitch going, just stand there for about 10 minutes. You will get the max amount of orbs, 199 full red bars which is 59,700 orbs.

Invictus Gladius
Invictus Gladius - Clear Sword Challenge 4.

Lots o' Orbs....kind of
After slaying Medusa when Aphrodite tells you to slay the minotaurs, don't use medusa's head. Instead, use poseidon's rage over and over again since you have infinite magic. There are infinite minotaurs. After a while the minotaurs don't give that much orbs so you should build a high combo. Maybe about 200+. It could be a little hard, but if you use poseidons rage at the right times, you can get a high combo for extra orbs. And you can always use the circle minigame on the minotaurs to get health if needed. Also, to avoid getting hit you can roll if youve powered up the blades at least once. If you are closely surrounded by minotaurs and use poseidons wrath (need to power up poseidons rage once and repeatly press circle) you will get a massive amount of combo hits maybe 50 or 60. Good Luck.

Lots O' Stuff
When you are in Athens after you fight the silverish minotaurs you will be on a road with a lot of houses. Inside the houses or on top of them you can find about 3 gorgon eyes, 2 or 3 pheonix feathers, and a whole lot of red orbs.

Lots of Orbs
When you get to the cliffs of madness and get to the part where you need to get the necklaces of Hera and Aphrodite, go past the two to the right, grab the chest, then go left. You'll find an underwater passageway. Go down and you will find a large pond with three breakable walls. Destroy them, and there are three chests, each containing a ton of orbs.

Mini Game
In the Beginning of Act 2, there are 2 women in your bed when you are inside your ship. If you jump on the bed, A circle will appear above the bed, indicating a Mini-game. Press Circle, and the game will start. All you see is the vase, but as you get further, the vase will shake more and more, until it falls and breaks. you have to press the buttons as it commands it. closer to the end, you have to rotate the Left Analog Stick. If you win, the first time, you get a large amount of Red orbs. Everytime afterwards, you get 5 more.

Move Faster
You can make Kratos move faster by rolling forward (press the Right Analog Stick forward) and cancelling the end of the roll with a Hermes Rush shoulder charge (press R1 when you've leveled up your Blades of Chaos). Repeatedly roll and shoulder charge to move forward at a much faster rate than Kratos' normal running speed.

Muse Keys
There are two Muse Keys hidden in the game, which are used to unlock a door in the Rings of Pandora. One is hidden in the underwater passage, after you've opened Poseidon's door; there will be a breakable wall that you can go through to reach an area with several enemies, breakable pots, and a chest containing the first key. The second key is found while going through the challenge of Poseidon, at the top of the ledges you must climb; simply go right when you've reached the top to find a chest with the second key. Once you have both keys, you can enter the room to obtain two Red Soul chests, and three fountains that will increase your maximum health, magic, and will give you five bars of Red Souls, respectively.

Orb glich
After receiving madussas gaze dont freeze the minators insted use posidens power over and over again to get orbs from the combo then freeze them with madessas gaze when finished getting orbs.

Power-ups
If you venture off the main course of where you need to go, you will normally find lots of red orbs, Gorgon eyes, and Phoenix feathers. So don't be afraid to wander, you may be sorry if you don't!

Secret 2 EU Version
In the European version of God of War you do not receive a telephone number scrambled up like in he American version. Instead you receive a secret cutscene which is ensued after destroying the Ares & Minotaur statues.

Secret Message 2
Destroy the Ares and Minotaur statues in the throne room at Olympus (use Lance of the Furies: L1+Circle). The secret message is a scrambled telephone number, just read it from left to right to figure it out... it should be pretty obvious. Call the number to get a pre-recorded message describing how cool you are (or aren't).

Secret Rooms
Right after you pass the three cyclops with rotating fists in Athens, and you pass the switching green/blue chest, you'll see a ladder. When you climb it, you'll see a dead guy draped over the rafter. Do a double jump over him from the very top of the ladder and you'll land on this thing with a red chest. Then jump to the room on the left to get some free orbs.

Right afterwards, you'll come to a ballista(giant bow/arrow thingy). When you turn the lever it spins around, BUT, after you shoot the door down you can spin it more and shoot through the walls on either side. (the room on the right is something you'll come to later)

Unlock A Secret Revealed
Beat Spartan mode.

Unlock Additional Costumes
Beat God of War Challenges.

Unlock Birth of the Beast
Beat game once (any difficulty).

Unlock Challenge of the Gods
Beat game once (any difficulty).

Unlock Character Graveyard
Beat game once (any difficulty).

Unlock Credits
Beat game once (any difficulty).

Unlock Deleted Levels
Beat game once (any difficulty).

Unlock God Mode
Beat game once (any difficulty).

Unlock Heroic Possibilities
Beat game once (any difficulty).

Unlock In-Game Movies
Beat game once (any difficulty).

Unlock Making of God of War
Unlocked from beginning.

Unlock Monsters of Myth
Beat game once (any difficulty).

Unlock Secret Message 1
Beat Spartan mode.

Unlock Secret Message 2
Beat God of War Challenges.

Unlock Teaser and Magic Teaser
Unlocked from beginning.

Unlock The Fate of the Titan
Beat Spartan mode.

Unlock Visions of Ancient Greece
Beat game once (any difficulty).

Weaken Ares
Right when you finish battling all of your clones, use Army of Hades. When you reappear next to ares in Athens, the spirits will still be there, and will weaken him substantially.