Here are some known hints and stuff that might prove helpful:
Brand New Fear mode
Successfully complete the game on any difficulty setting. Save the game after the credits complete to unlock the "Brand New Fear" option.
One Weapon mode
Successfully complete the game with a rank of 10 big stars to unlock One Weapon mode.
Full Weapons/Apartment Replenish mode
Achieve a 10 star ranking in One Weapon mode to unlock Full Weapons/Apartment Replenish mode. This mode has the following features: At the start of the game, upon entering the subway system you will see that each and every weapon is laid out in front of you. You can grab every one of them. Also, whenever you return to your apartment, you will find six boxes of bullets in the laundry room as well as ten Health Drinks in your refrigerator.
Chainsaw
Start a game in "Brand New Fear" mode. After entering the Forest World for the first time go to Jasper's car. Search near by for a cut tree trunk. Look next to it to find the chainsaw.
Submachine gun
Successfully complete the game with a rank of at least 9 big stars. Start a game in "Brand New Fear" mode and look in Room 202 in the Apartment World to find a submachine gun for Eileen.
Alternate Eileen costume
Start a game in "Brand New Fear" mode. Continue until the "Outside of Room 302" part of the game. Enter Room 303 and search it for Eileen's nurse costume. Collect it and complete the game. When you start a new game, you can now have Eileen dressed as a nurse.
Alternate Cynthia costume
Unlock all four endings and Eileen's alternate costume on a single game save. Start a new game and select Eileen's nurse costume. Cynthia will wear her alternate costume.
Knock on window
When looking outside, press [Action] and you may knock on the window. This trick has no use.
Call restaurant
When you look out your window, you can see the phone number of a restaurant. You can use the phone to call that number for fun.
Radio clues
Notice the suspicious radio in Henry's living room. At certain parts throughout the game, you will be able to listen to certain broadcasts. Listen to them carefully as they will be part of the story and clue you into what is going on. After you finish the subway, take out the chocolate milk and keep it in your inventory; then save and restart. When you reload, look through the front door peephole then go to the radio for a broadcast from Washington. They will talk about a 3 year old boy. Also, when you first use the radio in your living room, a report will come on about a man who was arrested for being naked and urinating in public. The name of the person is Suguru Murakoshi. He is the director and scenario writer of the game.
Guns
The use of guns is not necessary. It is quite easy to use melee weapons throughout the game. Also, using guns on ghosts prove ineffective unless the bullets are silver.
Batting practice
When remaining idle with the aluminum bat is equipped, Henry will begin to practice his swing.
Saint Necklace
Wearing the Saint Necklace, it has two uses to keep your "ghost sense" from causing actual damage, and to actually exorcise spirits from your apartment. When wearing it in any other world besides the apartment, the screen will do its usual haziness when ghosts appear, but nothing more until the necklace breaks. Keep in mind that the necklace will break if you are confronted by ghosts for too long. Wearing the necklace and running to a possessed area of your apartment will cause the spirit to fight back, but if the necklace is not already broken, the spirit will lose and disappear. Keep in mind that you must have your apartment completely exorcised for the good endings.
Sword Of Obedience
There is no need to waste a sword if you are just entering areas for items. Instead, knock the ghost down and stab it with the sword, get what you need, and take the sword back. After taking the blade out, you have five to seven seconds to leave without your "ghost sense" ringing out.
The Man's Doll
When a strange man places the doll on the stairway, do not take it. It actually makes things worse for you afterwards. If you place it in your storage box, babies will appear above the box, making it difficult to check your items. Your only choice would be to hold it in your inventory, but it requires a slot that you may need.
Mannequin body parts
When you enter the forest for the second time, go to the corner with the torch. Take the torch and take it to your laundry room in your apartment. Use the oil found on the workbench inside there on the torch. When you return, you may light it when you approach the other torches pressing [Action]. This is used to see down each well that happens to be in each corner of the map. Be cautious however -- if you use the torch to attack or unequip it, it will go out. This causes you to turn back to light it. Killing all of the enemies first and running from the man chasing you is recommended.
Midwhich Elementary school bus
When looking out of your window during the day, you will notice a school bus. If you look close enough, you will notice it is A Midwhich Elementary school bus. This is a reference to the original Silent Hill, where it is the school in which you visit within the first thirty minutes of the game.
Ghost Cynthia and the candle
Unlike most ghosts, if a candle is placed in front of the ghost Cynthia, she will stand in place and scream as her hair begins to float in every other direction. Other ghosts simply fall.
Eileen's behavior
When you are about in the building world for the second time, sometimes Eileen will act like the little kid and at other times act as if being attacked by a demon or act like a demon. Note: If you are near Eileen when she acts like a demon, it will affect you health.
Eileen's damage
If you allow Eileen to take enough damage, her appearance will change for the worst, and she will walk faster towards the pool in the final battle.
Eileen's Special Gift
Once you get to the wish house, after it has burnt down the mysterious writing in blood can be read aloud by Eileen. After some adjusting she will say "Okay...here goes..." and read the words.
Endings
To get different types of endings, you must do one of four things. Either clear your apartment of ghosts before the final battle, or do not; and let Eileen die or not. These two course of actions create four different endings.
on ps2 to drop out or to start from last continue point or even to go from last save point, hold R1 + R2 + L1 + L2 + START + SELECT. Might still work on a gamepad on the gog version.
Unlock Special UFO Ending
Finish the game 4 times to get the 4 different endings. Now play the game again using the same game save slot and pick Eileen's nurse uniform. Finish the game and hold Y and B before the ending to get the UFO ending.
