Unlimited Ammo:
During gameplay, go to the item selection screen. Press the following code depending on which version of the game you own. If the code is done correctly, the amount of ammo in each weapon will show an infinity symbol.

AMERICAN: UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, R Trigger - Unlimited Ammo

JAPANESE: UP, UP, DOWN, DOWN, LEFT, RIGHT, R Trigger - Unlimited Ammo

Unlockable Features:
Start a new game on normal. Then do the following:

Unlock TOFU - Start a game on normal mode with Claire A. Beat it and then beat Leon B. Then beat Claire A. Then beat Leon B. Then beat Caire A. Then beat Leon B. Make sure you unlock HUNK on the way, and get A Rankings with each scenario.

Unlock HUNK - Beat the A Scenario with an A Rank. Then beat the B Scenario with a B Rank.

Unlock TOFU - Start a game on normal mode with Leon A. Beat it and then beat Claire B. Then beat Leon A. Then beat Claire B. Then beat Leon A. Then beat Claire B. Make sure you unlock HUNK on the way, and get A Rankings with each scenario.

Extreme Battle Mode AND HUNK scenarios - Beat Leon A, then beat Claire B. Get A's on both scenarios.

Unlock SMG with unlimited ammo:
To get the SMG with unlimited ammo, beat either character's B game in under 3 hours with either an A or B ranking. You will see a special display telling you that you have unlocked it. It will be in the item box in the next game.

Unlock Gattling Gun with unlimited ammo:
To unlock the Gattling Gun, beat either character's B game in under 3 hours with an A ranking. You will see a special display after you beat the game telling you you got it. The gattling gun shoots buttloads of bullets at an enemy, and is very useful against a lot of enemies. It will be in the item box in the next new game.

Get new costumes:
Start an A Scenario with either Leon or Claire. Start the game, but DON'T COLLECT A SINGLE ITEM. Don't collect the weapon in the Gun Shop, any ammo. Go to the Police Station and down the stairs in the courtyard. A zombified Brad will be there. Kill him one way or another (by collect ammo in the RPD or stabbing him). Collect his ''Special Key'' and take it to the RPD Darkroom. Open the locked by the door and you get new costumes!

Secret Film (Film D):
Go to the S.T.A.R.S. Office with Leon or Claire. Search the Desk that says ''It's trashed. Someone must have searched the desk''. Search it 50 times! You'll get Secret Film D.

How to get all the Ranks:
S Rank: Beat the game in 1:30. Use only One herb. don't use any weapon upgrades, no special weapons (like the R. Launcer) and don't pick a weapon up more than one time, like if you pick up the shot gun from the weapon owner, don't go and get it on the police station.

A Rank: Beat the game under 3:00 and don't use any first aid, no special weapons.

B Rank: Just beat the game under 3:00

C Rank: Finish the game in 5 to 7 hours

D Rank: Beat the game over 7 hours

Extra Ammo:
Before you use the custom parts on the VP70(Handgun), Desert Eagle(Magnum) or Shotgun use the remaing ammo in the clip/breech. When you use the custom parts to upgrade the gun it will automatically be fully loaded. This may seem like a small amount of ammo but can go a long way in the harder difficuties were ammo is rarer.