바이오하자드 2 듀얼쇼크

Unlimited ammunition:
Press Select during game play and go into the "Key Config" screen. Hold R1 and press Square(10). The word "Manual" or "Auto" will turn red and all weapons will have unlimited ammunition. Also, the knife will never break.

Play as Ada Wong:
Unlock the EX mode and complete level 1 with either Leon or Claire to unlock Ada Wong for use in EX Mode. 

Play as Chris Redfield:
Unlock the EX mode and complete level 2 with any character to unlock Chris Redfield.

Play as Hunk:
Complete the first scenario, then complete the second scenario with the other character to play the 4th Survivor mission as Hunk.

Extreme Battle/Survival mode:
Select the "USA Version" option and begin game play. Complete Leon's first scenario and save the game. Then load, complete Claire's second scenario in "USA Version", and save the game. The typewriter will type "???" instead of Leon's second scenario. Load that saved game to start Extreme Battle mode.

Unlimited ammunition:
Begin game play and press Select to display the options screen. Select the "Key Config" option, then hold R1 and press Square(10). The word "Auto" will turn red to confirm correct code entry.

Stronger weapons:
Select the "Arrange Game" option at the main menu and play as a rookie. When you first start as either character, you will have the submachine gun with unlimited ammunition. When you get to the police station, you can find aid sprays, a shotgun, some ammo, a gatling gun with unlimited ammo, and a rocket launcher with unlimited ammo inside any box.

Alternate costumes:
Complete either character's first and second scenarios in less than three hours. A zombie in a uniform will appear after both missions are completed to confirm correct code entry. Load the saved game and begin the first scenario by going to the police station without collecting any items. Quickly move past the zombie that appears in the alley near the police station. Collect the shotgun, then kill the zombie. Take the special key from the zombie's body to open the lockers with alternate uniforms. Claire has a single alternate uniform, with a quick shooting revolver. Leon has two alternate uniforms, one of which will allow him to shoot with one hand.

Select original mode at the game selection screen. Then, go to normal game. Play through the beginning of the game without picking up any items (using the unlimited ammunition code is recommended). After reaching the police station, go down the stairs right next to the gate. You will see a zombie in a yellow vest (Brad Vickers from Resident Evil). Kill him and check the body for a "special key". Take this key and immediately head for the film developing room (dark room). There is a locker to the left when you first walk in. Use the key and Leon will get either an R.P.D hat, blue "wife beater" and green pants, or a bikers jacket with a skull on the back and black leather pants. Claire will get a cowgirls outfit and a Colt S.A.A (uses handgun bullets, but is faster and more powerful)

Play in Normal mode and get to police station without picking up any items (this includes ammo and herbs). Find the shotgun or grenade launcher or extra handgun ammo in the station then go back outside. Go into the underground tunnel and you will see a zombie wearing a yellow vest (Brad Vickers). Shoot him once with the shotgun/grenade launcher or several times with the handgun, then search his body to find a Special Key. Go to the darkroom in the police station and unlock the locker in the corner. Leon will find two alternate outfits (biker outfit or a muscle shirt with a baseball cap) and Claire will find one outfit (blue biker outfit with flames) and a new weapon (Colt SAA).

Unlimited weapons:
Complete either character's first scenario without saving the game in under 2.5 hours with an A or B ranking for the special rocket launcher. Complete either character's second scenario without saving the game in under 2.5 hours with an A or B ranking for the special gatling gun. Complete either character's second scenario without saving the game in under 3 hours with a A or B ranking for the special machine gun. The special weapon will appear in the next game after the first chest is opened.

Auto-aim:
Select "Options" from the main menu or press Select during game play. Then, enter the "Key Config" screen, select "Type C", and then select "Exit". The quick auto-aim feature should now be enabled. Hold R1 to get Leon or Claire to pivot and aim at any zombie they see, and press L1 while holding R1 is held to change targets. Note: You still have to hold Down to aim at crawling zombies and Up to aim at higher targets.

Hunk scenario:
Complete Claire or Leon's second scenario saving less than twelve times with a end time of under two hours and thirty minutes. Hunk is a soldier that must reach the second floor of the police station from the sewer with just battles and no puzzles. 

Tofu scenario:
Complete either character's first and second scenarios in less than three hours. Play the game again with the other character, and also complete their first and second scenarios in less than three hours. Play the game a third time and complete either character's first and second scenarios again in less than three hours. Note: The game must saved less than twelve times during each of the six scenarios played and unlimited weapons must not be used. Tofu is a piece of tofu (food) that must reach the second floor of the police station from the sewer with just battles and no puzzles. Tofu can not use any weapons other than a knife.

Ada Wong picture:

Search the desk on the left side of the S.T.A.R.S. office. The phrase ""Its trashed someone must have searched it" will be displayed. Repeatedly search the desk approximately fifty times until a roll of film is found. Take the film and develop it in the photo lab to see a picture of Ada Wong in a basketball uniform. 

출처 : http://www.gamewinners.com/playstation/ResidentEvil2DualShock.htm