The game starts off with Kratos slowly stepping off a cliff in a suicide attempt. You're left to wonder what brought about this action as he falls to his death. Just before he hits the rocks, you are brought back in time to three weeks earlier at the Aegean Sea.
Ship Deck
You'll start off on the deck of a ship, with some of Ares' soldiers (the Undead Legionnaire) blocking your way. Kill them with Kratos' blades, and practice using different types of attacks. The game also tries to teach you the basics of combat through subtitles, like 
to perform a light attack, and 
to perform a heavy one. Enemies can also be grabbed by pressing 
, opening up a new possibility for different types of combos. After finishing off the group of soldiers, another group will appear through the trap door in the ship. Defeat them and head on over to the trap door. Tap 
to open it, and then hop inside.
Ship Interior
When you get to the inside of the ship, you'll see a stone chest with a glowing green light. The light signifies what type of prize is inside the chest. In this case, opening the chest will give you HP. To open it, press and hold . Orbs that are usually gained from defeating enemies will fly out and go to Kratos. Now you'll notice that there is no way to go. Look for a structurally weak wall. Attack it and it will break, giving you a new path. Break anything else that looks weak to gain red orbs. You will now be told you can use 
to block.
Hydra: The First Head
Keep heading forward and one head of the Greek monster Hydra will break into the ship's interior. Keep striking at it but dodge when it tries to strike back. You'll know you're attacking it successfully when you see blood and the health meter at the bottom of the screen losing its green. After relentlessly attacking the head, you'll see the button above it. Press to start a QTE sequence. Keep pressing when you're told to. Kratos will finish off the head for now, and it will cower away after it is stabbed in the eye. You will gain an abundance of green and red orbs. Now is the time to power Kratos up. Press 
to open up the menu, and give Kratos some more power.
Hydra Aftermath
The Hydra head has not only torn a hole through the whole area, but also destroyed practically everything. The floor is now gone except for a few boards of wood. You must now balance Kratos across the boards and to the other side of the ship. Jumping is risky, but can be a shortcut. Keep in mind that, although Kratos may catch himself before he falls sometimes, he does have a large chance of falling off, leading to death. After getting to the other side go through the opening in the left to see a caged soldier. Talk to him to see what he really thinks about Kratos (apparently, he'd rather die than be saved by him) and just leave him alone. Go to another opening to the right and walk up the staircase to see a chest. Open it and keep walking. You will then be told that you can use 
to evade and dodge attacks made to you by minor enemies and bosses as well. Your path will be blocked. Once again, break it open with Kratos' blades. You will then see a door you will be able to kick open with .
Ship Deck
Here you will meet new enemies, looking similar in appearance to flying demons. Though they have a special advantage over Kratos with the ability to fly, Kratos can still attack them just fine from the ground. Next to the door will be two other doors that must be lifted. Tap to find chests. Go back to the middle and the second Hydra head will pop right out of the ship's floor.
Hydra: The Second Head
This Hydra head will use different attacks due to its position. Instead of jabbing at you with its teeth, it will slam its head around the deck to try and smash Kratos. Your attack strategy should be nothing new. Evade its head and keep attacking with your blades. Once in a while it will swing its head right around. Jump quickly before he can hit you. It will also grab Kratos up into its mouth, which leads to a quick sequence of tapping . It will grab you in its mouth two times. The third time, it will cower away and you will get your reward of green and red orbs.
The Flooded Interior
Dive through the hole the Hydra head leaves behind. You'll be able to go underwater for an unlimited amount of time. Swim through the small opening and you'll see a large net at the end. Jump against the net and press 
to climb up the net.
Ship Deck
You'll meet some more Undead Legionnaire on the deck. You'll be told you can press and hold to launch them into the air. Defeat them. Now you'll see that you're at the end of the ship. There will be a pole positioned on the deck to lead to another location. Balance on the pole and walk across. There will be two other poles to walk across after crossing the first one. Cross the one that's going straight to reach another ship.
Ship Deck 2
When you reach the next ship, a cutscene will ensue. Arrows are being thrown at you by armed Undead Legionnaire, who are all the way on the other side of the deck. This calls for some stealth. First though, you are given a chance to save, the save point being a light. After saving, jump down onto the lower deck to see some dying soldiers of the Spartan army. Though you will have to take cover, you also need to bring one box all the way to the front to give you a boost to the higher deck, where the Undead are shooting from. You will be told to hold and charge 
to kick the box. Be careful though; the box is a little weak, and will break if arrows are shot at it. This means you'll have to start all over and go back to where the box has regenerated. When you take cover, take the box with you. This is when you are told you can press and then again to double jump. Double jump up and kill the shooting soldiers. Open the treasure chest in the opening and go through the door on the left.
Going Up
After going through the hall, you'll see a door that, if gone against, gives you the chance to press . Instead of giving you the chance to take action, you are told it is where the women are hiding from the massacre, which happens to be the Captain's Quarters. You'll need to find a key to open it. Climb the ladder to see a net. Start climbing on the net. Unlike the net you've seen in the flooded interior of the first ship, the Undead will be climbing on this net, and they'll be trying to hurt you. Move 
in the direction the soldier is, then for a quick jab of Kratos' blades on the enemy. You can also move in the direction of a soldier and press for a long swipe. After climbing up the net, you'll land on a round platform only to see another net. Climb up that enemy-infested net as well to reach another round platform. Kill the Undead here and jump on the rope to slide down it.
Poseidon's Rage
Smash the wooden boards blocking the chests and open them. One will contain a Gorgon Eye. Collecting six will increase your maximum health. The one on the left will contain the usual orbs. Smash the boards in the middle to find a narrow hallway. Go through it to see a glowing blue wall and a blue save point flanked by two tall statues. Touch it to initiate a cutscene. You'll see the face of the God of Water, Poseidon. He tells you that, before you can reach Athens, you must fulfill a task: defeat Hydra. He will give you Poseidon's Rage to assist you on your quest. Press 
and then 
to activate the new power, which will let you use lightning.
Hydra: The Final Battle
Go through the opening the face has left, which will lead you outside. Use the save point if you wish, and on the side opposite the save point will be two treasure chests. One is the usual health, but the other will introduce blue orbs, which give you power for magic. Keep going right and climb up the net. A cutscene will follow showing Spartan soldiers trying to fight off the third Hydra head. One of the soldiers is eaten up, and another tries to run away before running right into a second Hydra head, who swallows him. The third soldier is chewed up by the first Hydra head. Now only Kratos is left, and he isn't afraid. Now you will have to face all three Hydra heads.
Hydra Heads 1 & 2
The two smaller Hydra heads on the left and right of the larger one will be the ones you have to tackle first. Use the same strategy for both. Slash the head until it goes down and start to climb the boxes. When you reach the platform at the top, jump on it and Kratos will bring it down with his weight. It'll go down on the head, trapping it no matter how much it struggles against it. After trapping both heads, move on to the last one.
Hydra Head 3
Climb the net and you'll see the largest head, the third one. Keep slashing at it, and use Poseidon's Rage when it gets close enough. When it roars, hang off the ledge instead of having to go all the way down. After hurting it enough, the head will go down. This is when you press . Kratos will grab it by the mouth and try jamming it into a pole. Tap and the pole will break a little. Repeat this and the pole will get weaker and weaker, and so will the head. After a couple of jams, another large above the head. You will enter a QTE where you will again press . Tap to get the Hydra's head through the pole by the eyes. It will eventually die and the other heads, without the support of the third and largest one, will also die.
Captain's Key
After the cutscene, go into the Hydra mouth right in front of you. When you reach the end of the throat, you'll see one of the soldiers who was swallowed by the Hydra head, who happens to be the captain. Unlike the other soldiers, he wasn't chewed up, so he's still alive. Press to activate a cutscene in which Kratos lets the captain die but takes his key. Go back out and climb up the boxes on the right to see a net. Climb up the net and open the treasure chests. One of them will contain the second Gorgon Eye. Slide down the rope once you're done. Jump down onto the deck and jump down onto the lower deck. After killing the Undead Legionnaire, jump on the box you placed there earlier and climb up the net and onto the upper deck. Go through the opening and you'll be back outside. Open the door you couldn't open before by pressing . Go through the door and follow the path to find another door. Open it with and you'll see a long cutscene bringing you to your next destination.