NOTE: Silent Hill 3 has different costume codes, depending on the region; these codes are for region PAL, which includes the United Kingdom and Europe)
Finish the game to access the secret costume passcode screen. Enter the passcodes to unlock a new costume for Heather:
Press L1 + L2 + R1 + R2 on the options menu. Note, that dying twice on Normal unlocks Beginner Difficulty which can only be found on the Extra Option menu.
Unlock New Weapons (PAL)
Unlock new weapons by playing through the game and then doing the following to affect your final score:
Flamethrower
Kill more enemies by shooting with ranged weapons than by fighting with melee weapons. You can unlock the flamethrower the sure fire way by clearing the game twice.
Light Saber
Kill more enemies by fighting with melee weapons than by shooting with ranged weapons.
Silver and Gold Pipe
Throw the normal (steel) pipe into the sewer and answer the next three questions as, "No", "No", "Yes".
Unlimited Submachinegun
Destroy the last boss in the game with a melee weapon. Easiest if you use a Gameshark device to set Heather's life to "never die".
Douglas Wearing Y-Fronts
Beat the game then highlight New Game (Extra) and enter the old Konami code (press UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, CIRCLE, CROSS). Select your difficulties and a sound will verify the code. Douglas will be sans pants when you see him through the game.
References To SH2 (PAL)
NOTE: This requires a save game that is a PAL version of SH2. The game also needs to be listed as a cleared game.
Using any memory card with a finised/game cleared file from Silent Hill 2 will cause some retroactive interactivity when Heather investigates some areas of the game.
Heather Beam
Kill 333 enemies or more.
Beam Sabre
This weapon will turn into a 'Sexy Beam' when you have the transform costume equipped.
View 'possessed' ending
Kill more than 100 enemies, forgive the person at the church and get more than 2000 points worth of damage.
Beginner fighting difficulty setting
Intentionally die twice during game play under the normal fighting difficulty setting. The fighting difficulty setting can now be set to "Beginner" in the extra options menu.
UFO ending
Successfully complete game and unlock the Princess Heart costume and the Heather Beam weapon. The Heather Beam is a special weapon which you can only use if Heather or Cheryl is not holding any weapon. Defeat all monsters and Bosses using only the Heather Beam. Note: The "Monster defeated" counter should read 0 kills.
Normal ending
Beat the game simply by not killing too many enemies.
Unlock the Life Bar
Complete the game on Hard Action Mode and Hard Riddle Mode to unlock the life bar, which can be turned on and off at the extra options screen.