1 hit Gator kill:

Here's a secret trick to kill the Gator boss. When he starts advancing on you, you'll notice a yellow light on the left wall. Push the X button and a canister will fall to the ground. When the Gator chomps down on the gas canister, shoot the canister and the Gator will blow into bloody chunks!

Infinite Submachine Gun:

Beat either alternate scenario with an A or B ranking without using any health sprays

Infinte Gatling Gun:

Beat either alternate scenario with an A or B ranking without saving.
Submitted by codeman10

Infinite Rocket Launcher:

Beat either regular scenario with an A or B ranking.
Submitted by codeman10

Play as Hunk:

Beat the regular and alternate scenarios with either character and get an A rank. Then you will get the option to save to a normal character with infinite weapons, or another scenario. Pick another scenario and you will start a quest with a character named Hunk. He's an Umbrella SWAT soldier who has his own problems...
Submitted by codeman10

Play as Tofu:

This one might take a while. Play all 5 possible scenarios (Leon 1 and 2, Claire 1 and 2, Hunk). Now save and you will start a new game with a new character. His name is Tofu and he's, well, a big piece of tofu. However, you can only use a knife with him (and why zombies would want to eat tofu is beyond us.)
Submitted by codeman10

Change your Clothes

start a game on original
ormal and go to the police station without collecting any items and a super zombie will appear. This new zombie is actually Brad Vickers from Resident Evil 1 (the chopper pilot). Kill him pus the action button to grab the Special key to a locker in the dark room. now you can change your clothes. this code will not work if you pick up any items.
Submitted by Rodney Clark

Shoot the Camera

go to the outside area in the basement where the two dogs jump down from the fence,stand with your back facing the manhole and walk forward until the camera angle changes.Now shoot you rifle at the camera and bullet holes will appear on the TV screen.
Submitted by MITCHELL CORDELL

Locker Room

Start off the game pick normal mode. Then pick either character. When you start off the in the beginning in the streets do not pick up any items, not ammo not the shotgun, no health spray. Go all the way until you reach the police station go down stairs and you should see a zombie but he's no ordinary zombie. He'll take a few shots before he dies. Once you kill him you should get a key that opens up the locker in the photography room. In the locker are knew outfits for both characters, Claire should also hav a revolver.
Submitted by Kerberos1359

Secret Photo

In the S.T.A.R.S office find a desk that gives you a message that says"it's trashed,someone must have searched the desk......."now check the desk and the 50th time you check it you will receive a photo return to the "Black Room" develop the film and you will get a picture of Rebecca from the original Resident Evil.