Yes, the ending of Chapter 3 of Resident Evil 4 Remake confirms that chapter endings are all about cliffhangers or something. We have nothing against that, but come on—we know the blond guy is going to survive, so stop keeping us on edge all the time. When you regain control of Leon, you will be unable to use the boat, as it sinks. Follow the only available path.
Cross into the next room, where you will find some resources and a police officer's cap to examine, then continue along the path. Believe it or not, there are no threats here, so explore the area to collect some resources before following the tunnel to the south. Immediately afterwards, you will have your first encounter with a mutated Ganado, whose Plaga has emerged from its head and taken control.
As you will see, the bladed tentacle has a fairly long reach, the creature moves quickly and will not stagger if you shoot its human body. You must attack the parasite itself with something powerful, such as the Shotgun or Rifle. One trick carried over from the original is that a Flash Grenade will instantly kill any exposed Plaga. Keep this in mind if you encounter several of them, have a grenade available and do not want to take any risks. Another one will appear immediately after the first, so be careful.
As you continue, you will reach a cave containing the key you are looking for, although you cannot collect it yet. There are two stone hands on either side, and you will obviously need to place something in them that you do not have yet. Remember this location.
Examine the mural in the next room to have two locations marked on your map. These will become your new objectives. Continue until you leave the cave, making sure to collect the Old Wayshrine Key beside the shore. This key allows you to open the special wooden shrines with unusual locks. Do not worry, as we will point out the location of every one as we progress.
Make sure you activate the Egg Hunt request, which we will complete while exploring.
Start by heading west to the Merchant and then go south to the dock, where you can take the boat to the southwestern area.
You will find several items and enemies here, as well as yellow paint on some of the columns. Pay attention to the symbols it forms.
When you reach the highest point on the eastern side of the area, you will find a locked door and a device with several discs. Press the buttons bearing the symbols you saw on the walls, in any order. If you do not want to make things difficult for yourself, the solution is shown below. Pay attention to the symbols in case the button layout is different:
Inside, you will obtain the Apostate's Head key item. Before returning to the boat, do not forget to shoot down the lantern marked as a treasure in the area to collect a Velvet Blue. Now take the boat west along the river until you reach another dock at the westernmost end.
The treasure map marks two items in this area. One is an Alexandrite, a new type of gemstone. The other is the first Wayshrine, which requires the special key you collected earlier and contains a Splendid Bangle.
Return to the Lake and use the map to locate the treasures in the middle of the lake. They are aboard a wrecked boat. Approach it from the side to disembark and collect another Alexandrite. Leave through the other doorway and head to the bow to find a large chest containing the Red9 handgun, or a Gold Bar (L) if you already have it. Return to the boat and head to the eastern end of the lake, where you will see an area of land that should have a treasure marked on the map.
This area is home to several chickens. At the easternmost point, behind a rock, you should find the Golden Chicken Egg required for the request. Collect the Velvet Blue as well. Now head to the northeastern corner of the lake, where you will discover the Large Cave Shrine.
Here, you will encounter another disc puzzle. This time, you must stand in certain positions to identify the correct symbols. You can see them by climbing the stairs to the left of the building and looking at the stalactite, through the window to the left of the stairs and beside the ladder. If you do not want to work it out yourself, this is the solution:
Inside, you will find a case containing Hexagon Piece C, as well as the Blasphemer's Head. Climb the ladder to find a lantern that you can shoot down to obtain a Ruby. You can technically continue with the story now, but do not do so yet. We are going to take a detour to collect a ridiculous number of items and treasures.
Start by heading to the northwestern shore. You will reach the house where Luis was being held, but you can now collect a couple of treasures: the Red Gemstone Ring from the basement where you found him and the second Wayshrine, which contains a Pearl Bangle.
The northern door, which you can unlock with the Insignia Key, leads to a small detour. Head northwest to activate the Catch Me a Big Fish request. Now open the other door, examine the body, collect the available resources and climb the ladder. You will reach the Forest Altar, where there are several more items. You will find a Small Key on the cart on the western side. Make sure you also destroy Clockwork Castellan #04.
You can now return to the house where Luis was being held and open the locked drawer. Be careful, as dogs with mutated parasites will appear when you approach. Inside the drawer, you will find a Gold Bar.
Now that you have all three Hexagon Pieces, head to the area southwest of the Lake, where you first obtained the boat. You can insert all three pieces into the stone pedestal on the western side.
If you are following our walkthrough, you can find the solution to the puzzle here. If you have already moved any of the pieces, tough luck, mate. Once you form the circle, you will obtain the Depraved Idol. On your way back to the Merchant, make sure you catch the Lunker Bass so you can hand in several requests at once. The Merchant also has another case capacity upgrade and several other items, so buy whatever interests you.
You can now return to the main objective marker, place the two heads on the stone hands and collect the Church Insignia. You must now retrace your steps through the Quarry. Along the way, you can open the third Wayshrine, which contains a Butterfly Lamp.
Continue a little farther and, as you will probably remember if you played the original, it is time to face El Gigante.
Simply keep your distance and shoot it in the head. If it leaps towards you, watch for the Evade prompt, and if it charges, run to one side. Once you deal enough damage, a Plaga will emerge from its back. Shoot this weak point to inflict as much damage as possible. At first, you will be unable to climb onto its back when it drops to one knee, so simply attack it with your most powerful weapon. You will receive some help during the battle, and a couple of sequences will play. Take advantage whenever the creature is immobilised to attack.
When it drops to one knee, approach it and you will see the Melee prompt, allowing Leon to climb onto its body and repeatedly stab the Plaga for additional damage. By this point, it will not have much health remaining and should fall fairly easily, leaving behind a Yellow Diamond.
Make sure you collect the resources scattered around the area. Once you return to the church, insert the insignia into the door to open the gate and enter. On the ground floor, beside the altar, you will find a Small Key. If you wish, head back outside and return to the basement area to open the locked drawer and obtain a Yellow Diamond. Back on the church's ground floor, collect a couple of items and the Blue Dial from the southern corner. Activate the lever beside the altar to reveal a mechanism into which you can insert the dial.
To solve the puzzle, rotate the dials until they are arranged in the following position:
You can now climb the stairs at the side. When you reach the room upstairs, a cutscene will play and you will proceed to Chapter 5.
