Resident Evil 4

At the beginning of the game, if you leave a hen alone in Pueblo they should lay at least one golden egg. Go to the weapon/health screen and select the egg. It should allow you to equip the egg. At the screen, Leon will throw the egg up and down, looking smug.

Leon can't leave Ashley when he transitions into a new area (signified by the blurring effect); however, he can leave Ashley safe in the corner of a dangerous area then call her over when its safe. You can instantly tell if Leon is about to leave an area if the open or context command is printed in green. If the command is printed in white, Leon will simply open the door to another section of the area. Use this to plan out where Leon can leave Ashley to brave the dangers ahead.

At the start of the game you'll find a dog stuck in a bear trap. If you go over and free it from the trap it will help you later during the second boss fight.

Near the church in Chapter 1-3, instead of going up to the church, take the path towards the lake. This will trigger a conversation with Hunnigan, where Leon stumbles with words.

If you don't push any buttons at the title screen. Then after about a minute or so a never-before-seen trailer will play. If you do the same thing at the title screen after the 1st trailer has played then the trailer from The Tokyo Game Show of 2004 will play. It will play these 2 trailers for as many of times as you don't push any buttons at the title screen.

When you first get to the village and you are having trouble escaping the chainsaw maniacs and other enemies, you can hide in a safe spot. Go to the tall tower in the east side of the village (check your map) and climb up the long ladder. The villagers cannot climb that particular ladder. This also works when you need to place Ashley in a safe spot when exploring this particular area.

Crocodile: When killed, do not cut the rope.
Giant insects: Let them vomit on you.
Trap door floor: Salazaar will enjoy sending the spikes impaling Scott Kennedy.
Knife fight: At the end, let him press the knife through the cavity.
Two Los Gigantos: In the magma floor/pool, activate the switch and stand next to the pool.
Chief Mendez: In the barn fight, do not evade his grab in the intermission sequence

Note: Save before each encounter before trying to see the following death scenes.

Later in the game, the Merchant has a gun called "Killer7". This powerful magnum shares the name of an upcoming title by Capcom called "Killer 7".

Throw a flash grenade in the middle of a group of birds. All of them will die instantly, leaving lots of gold. This also works with the Granadas when their heads are transformed.

You can kill the merchant at any time in the game. Under the normal difficulty setting, he just dies then comes back at the next place, or when you leave the room and come back in. However, under the professional difficulty setting, once he dies, he remains dead. When you see the merchant and his eyes are glowing red, you can take the mine thrower and shoot a couple of darts. Most of the time he will turn into a blood stain on the floor.