After regaining control, you will find yourself at the outskirts of the city (some of you might already know this place, as it has been used in the demo version). Don't waste time and head forward.
Right behind the corner (a surprise for those of you who have played the demo), Gaia will ask you for help. However you will treat her just as she treated you. Begin attacking the damaged hand, and once the QTE mark appears, activate it. Repeatedly press L1 and R1 and afterwards throw away the hand and move on.
This way you will arrive at a closed door. For it to open, you will have to face a new type of enemy - undead armoured soldiers.
The tactic is similar to the one used against normal undeads. Block from time to time, but mainly focus on attacking constantly, without any more complicated strategies.
The only difference is their armour, which prevents you from grabbing them at any given moment (only after a QTE symbol appears). They also have the ability to attack from a distance - from time to time they will hit the ground with their swords and create a shock wave. Jump over it to avoid losing health.
After dealing with the enemies (including undead dogs that will appear), go through the opened door.
This way you'll arrive at a cave. You'll have to move from one ledge to another. Nothing new for the people who've played the demo, but a little explanation is required for the others. Firstly, shoot the harpy for it to approach you. Afterwards grab it by pressing L1 + Circle. Now all that's left is to fly over the gap and press X at the end to do a jump.
In case of the second gap (if you jump down into it [RS], you will find an experience chest), the method will be the same, but you will have to grab onto a second harpy (it will be highlighted once it's close enough, press X to change carrier).
On the other side there's a save point and chests with health and mana.
There will be no more enemies until the end of the cave.
After getting outside, fly over the gap and get ready for a fight. Armoured undeads will be the first to arrive. After you deal with them, a Centaur will join the fun (you've already dealt with one at the beginning of the game). That's not all, as Helios is flying around the place and occasionally firing missiles at the arena.
Despite that the fight won't be too hard, neither of the enemies is too tough. After you've dealt with them, head left.
As you go up, you will have to face a new, more demanding enemy - the Chimera. Try to fire the ballista and it will appear.
After the fight's over, operate the ballista once more and release as Helios shows up. This way you will destroy his divine chariot.
The Chimera fight has three phases and during each one the enemy will not only use different attack, but also behave differently. At first, you will be attacked by the snake. He uses normal attacks (medium range) and spits acid from time to time (also medium range). If he does hit you with his acid, you will be stunned for a while and will need to move the left stick to quickly regain control. The first phase ends with cutting of the tail during a QTE (one basic button).
During the second phase you will have to fight the lion part. This time you will be mainly attacked with the tail. The Chimera also three-burst attack (if it does, quickly dodge). You can also get attacked by a two-hit combo with his paws. Eventually you will get the chance to activate a QTE during which you'll need to quickly press Circle.
This time you will have to face the goat, it's very agile and also uses fire attacks. He can jump at you from a distance (jump or use the right stick to dodge) and breath fire (jumping works well here). During the QTE you'll have to press one of the basic buttons and then mash Circle.
Afterwards return to the place where you fought the Centaur a minute ago and approach the destroyed part of the wall.
You'll have to cross the gap to the other side. Wake up the Harpy (with the bow) and fly to the other side, changing the carrier several times during the flight.
One the other side you'll be attacked by a group of armoured undeads - kill them and enter the building (after the first straight, you'll find an experience chest on the left [RS].
Move on to face another group of enemies. There's quite a bit of them, so consider using heavier attacks or incinerate them with the bow. After another straight corridor, before you go right, check out the left side to find an experience chest.
After getting outside go through the bridge and go up the ladder on the other side. It's time for some platforming action. After going up the ladder, you'll fight yourself on a narrow ledge. Go right until you reach some burning windows (there won't be any explosions, so don't worry). Throw down the mortal standing by them, grab the ledge (R1) and avoid the flame.
Afterwards jump onto the construction on the right and go up.
You will find Helios there, but before you have the chance to fight him, you'll have to face a new type of enemies - undeads with shields.
Unfortunately none of the weapons you have at the moment will damage them. Hit them a couple of times and a Cyclops will appear. Take control over him and destroy the enemies which are defending the god.
The Cyclops is a surprisingly easy enemy, especially considering his size. During the fight, he'll use his hand, mace and feet to damage you. Each attack (apart from the one with the mace, which has a longer range) is close range. Once you deal enough damage, a QTE symbol will appear above his head. Activate it and press two basic buttons.
This way you will jump onto his back and take control over him. You will have two attacks available, with the Square and Triangle buttons. The Triangle one is a bit slower and more powerful, but even the Square one is strong enough, considering the Cyclops' size, so you should focus on using it. After about a minute the ride will be over, and Kratos will automatically proceed to killing the enemy. In order do to that, you'll have to mash Circle.
Approach Helios and a conversation will begin. Afterwards the god will try to attack you with a blinding light [RS]. A mini-game will begin, during which you'll have to block the light source with your right hand, using the right stick. If you do it properly, Kratos will approach the enemy and attack him - mash Circle.
That's still not all. After a short talk Kratos will attack him again. Mash Circle and then quickly tap L1 and R1 to rip off his head. This way you will gain Helios' Head.
It has several functions. Basically, you can use it as a flashlight. It comes in handy in dark places (one of them in just a moment). You can also blind enemies and irate them with it after charging up the head (both attack also damage the enemies a bit). They also lighten up the area for a short period of time.
The head can also be used to expose hidden items and passages. Gold dust can be found near those places, which makes finding them easier. Point the Head at it to unveil what's hidden there.
Before you move on, approach the dead body to find another item - Helios' Shield.
Now you can approach the big wall and point the Head at it. This way you will unveil a secret passage. Behind it there's a dark tunnel with a couple basic enemies - a good place to check out your new gadget. Move forward to arrive at a vast cave.