Resident Evil 4

Completion bonuses
Successfully complete the game to unlock the Separate Ways and Mercenaries mini-games; the Professional difficulty setting; Leon's Raccoon City Police Department costume, Ashley's pop star costume, and Ada's black costume; the Mathilda handgun and Infinite Rocket Launcher for purchase (for 1 million Pesetas), and the Tactical Vest (for 60,000 Pesetas); and an alternate title screen. After completing the game the first time, start a new game, then press Start and select "Load Game". Choose the file that is marked "Clear". Once you choose that file, you will be taken to a menu where you can buy the Matilda Handgun or the Infinite Rocket Launcher. Once you start the game, all of your items from your previous game will be in your item box.
Successfully complete the Separate Ways mini-game to unlock Ashley's knight costume and Leon's gangster costume. Ashley's suit of armor is bullet and damage proof. She cannot get hurt by anything and it is so heavy she cannot be carried away. You do not have to worry about giving her First Aid Sprays, Herbs, or shooting Ganados trying to pick her up.
Successfully complete the game in Professional mode. The merchant will give you a PRL 412 laser cannon when you start Round 2 of Professional mode.
Chicago Typewriter
Successfully complete the Separate Ways mini-game to unlock the Chicago Typewriter (Tommy gun with infinite ammunition) for purchase (for 1 million Pesetas).
HandCannon
Get a five star rank with all mercenaries in the Mercenaries mini-game to unlock the HandCannon weapon. To get unlimited ammunition for it, fully upgrade all of the HandCannon's options. Alternately, successfully complete the game two times. The HandCannon will be available as soon as you start the game again for 0 Pesetas. It is a very powerful magnum, and will have unlimited ammunition. When you go to upgrade it in the merchant window, in the "HandCannon" update screen there is an option labeled "Exclusive". When chosen, the gun is upgraded with power identical to the Chicago Typewriter.
Punisher
Destroy at least ten of the fifteen blue medallions (there are seven in the farm and eight in the cemetery) to get a free Punisher from the Merchant two guns before you can buy it. This pistol hits two targets when you get it and five when you get exclusive.
Bonus characters in Mercenaries mini-game
Get a four star rank in the following areas to unlock the corresponding character in the Mercenaries mini-game:
Ada Wong: Pueblo
Albert Wesker: Waterworld
Hunk: Island Commando Base
Jack Krauser: Castle
Mercenaries mini-game tips
The main monsters to look out for are the two chainsaw ladies on stage 1. Once you kill them, they keep coming back. On stage 2 and 3 be careful of the guys with the chain guns. On stage 4, there is a super chainsaw man. He is bigger than the normal one and has a twin bladed saw. He is almost impossible to stop. He does not climb ladders. He jumps to where he needs to be. He will run at you, swinging the saw. Do not run past him. Turn and jump down if you can, or climb something quickly. If you really want to get past him, try using Jack Krauser's transformation, and aim right at him. If you miss, you are dead. Additionally, Krauser's transformation will kill anyone in one hit as long as you are close enough. Also Flash Bang, Kick are very good for crowds with Krauser. These two things will make Krauser the easiest to get five stars with.
Easy completion in Mercenaries mini-game in Village
Go to the top of the barn (located next to the house where you found the shotgun in the main game). There is also a timer under the ladder, and a chest above, and up the ladder. Go up there and wait for the Los Illuminados to come to you. When they are mostly packed in, shoot the barrel inside and jump down quickly. Get what they dropped. Get back up the ladder and repeat. Note: Do not throw a grenade while there is a flame barrel down there; it will not do twice the damage. Also, be careful of the Chainsaw Hags that appear. They will cut off your head if you get too close. It is best if you are Hunk or Krauser to use the neck break; and the transformation of Krauser's arm, which kills them in one hit. With Ada or Wesker, use their sniper rifles until they are both gone, then jump down, With Leon try grenades, but it is very difficult.
Easy completion of Professional mode
The best way to complete the game in Professional mode is to first complete the Separate Ways mini-game. You will unlock Ashley's knight costume and Leon's gangster costume. Selecting Ashley's knight costume makes Professional mode a lot easier. Ashley cannot be injured or carried away. Use her for bait when needed. At least half the enemies will go directly for her, giving you time to kill them and keep your distance from a crowd. This also works well on El Gigante.
Control title screen
At the title screen, press the Right Analog-stick to move the background. Press R1 to zoom in or L1 to zoom out.
Game trailers
Remain idle at the title screen. Eventually two trailers will begin playing and begin to cycle.
Extra scene
When Leon is being choked by Chief Mendez, he will be told that he has the same blood. Leave the room, then return. You will be choked again by Chief Mendez, only this time Ada will come to the rescue.
Extra ammunition
Wait until you are low on ammunition before upgrading a gun. The replacement gun will always have a full clip, giving you extra bullets that otherwise may be difficult to find.
Easy money
Once you gain access to the tunnel with the merchant beyond Pueblo, return to the farm area and wait for the chickens there to lay eggs. Exit and re-enter to begin the same process over again. After you fill your inventory, you can return to the nearby merchant to sell your eggs. White chicken eggs sell for 300 Pesetas, brown eggs for 600 Pesetas, and golden eggs for 3,000 Pesetas.
Quick money or more health
If you mix a Green, Red, and Yellow Herb, you can sell it for a lot of money, or use it to restore health and increase the maximum health. Use it when you are low on health so that you do not waste the health recovery from it.
Open doors quicker
Tap X(2) when the "Open" action appears to kick open or down some doors instead of nudging them by hand. This will give you an advantage, as any enemies behind the door will be sent flying back.
Opening locks
There are many locks on doors. Instead of shooting the locks and wasting ammunition, pull out your knife and cut it off. The same can be done for boxes.
Aim faster
Use the D-pad and Analog-stick together to aim faster than normal.
Avoid damage from traps
To avoid getting hurt by traps such as explosives and bear traps, use your laser sight and shoot at the explosive or the middle of the trap.
Finding items
To find items, smash all of the crates with either your knife or a gun.
More items
When running around different areas of the village, you will see crows. Pick them off from a distance as to not scare the others away. They usually drop Pesetas. Note: If you scare some away, just re-enter the area to reset their position.
Selling items
If you plan to sell two or more herbs or other items that can be combined, combine them first and do not sell them separately. This will result in a small boost in the total selling price when compared to what it would have been if you sold them separately