Enter these cheats at the code input screen in the Options menu: 

Code - Effect
ANGMINGT - Full Rage
MMMYHLP - Half All Enemies HP
FSTOFRY - Wicked Punch
BRCESTN - Puzzled Solved
GMMSKIN - Invincibility 
FLSHWND - Regenerator 
GRNCHTR - Unlimited Continues 
HLTHDSE - Double Hulk HP 
BRNGITN - Double Enemies' HP 
MMMYHLP - Half Enemies' HP 
NMBTHIH - Reset High Score 
TRUBLVR - Level Select


Codes:

Enter these codes during game only (find a Game Terminal to enter them) : 
Play as Gray Hulk - JANITOR 
Unlock Desert Battle art - FIFTEEN 
Unlock Hulk Movie FMV art - NANOMED 
Unlock Hulk Transformed art - SANFRAN 
Unlock Hulk vs. Hulk Dogs art - PITBULL 


Defeating the parasitic Half-Life: 
Half-Life is the first Boss you have to fight. His touch will drop your health. Get him 
into the generators. If you cannot; jump into the air and press Gamma. If you get 
him in a generator, you will fry him. His bar will return. Use the same strategies 
again. He will return after you defeat Ravage (Gamma thief).

Defeating soldiers with their shields up:
When you are in rage mode and encounter soldiers in their shields, do Hulk's 
Earthquake attack. Their shields will fall and you can take them out .

Destroying missiles:
Perform any kind of punch toward a missile when it is flying at you. If timed 
correctly, you can punch the missile and it will fly back to the soldier who shot it 
then blow him up.

Destroying helicopters:
If you get something to throw, pick it up then jump on the roof. Jump while on the 
roof. If done correctly, you can blow up the helicopters.

Do a Super Sonic Clap while in a rage. Point in the general direction of the 
helicopter, do the attack, and it will explode. Note: This will not work if the 
helicopter is directly above you.

Betrayal: Falling soldier:
Grab a soldier and jump off the building where green arrows are pointing. As you 
land on another building, the man will disappear from your hands and you will hear 
him screaming. 

Chemical Effects: Terminal:
When the level starts, go all the way down the hallway to Bruce Banners left. You 
will find a large door. Go through that door and either sneak past or defeat the 
guards. There should be a door to the left of you. Go through that door. Once 
through it, either defeat or sneak past the guards. Next, stand in the large circle 
with bars around it. Press Y at the screen inside of the circle with bars around it. 
This should take you to the fifth floor. Once there, you should see a large 
computer down the stairs. Either defeat or sneak past those guards. Go to the 
right of that big computer. You should find a smaller gray computer. Go to it and 
press Y. A code terminal screen should appear. Enter the desired terminal code. 
Note: Per game, you can only open up the code terminal once. Use it wisely unless 
you want to repeat the entire process.