Press R1(2), L1, R1 at the main menu. A message at the bottom of the screen will confirm correct code entry.
Exploding fists
Press R1(2), Triangle, Square, Circle, R1(2) at the main menu. A message at the bottom of the screen will confirm correct code entry.
Flame on
Press Circle, Triangle, Square, Circle, Triangle, Square at the main menu. A message at the bottom of the screen will confirm correct code entry.
Hero mode
Press L1 + Triangle with a full special meter.
Hot fists
Press L1(2), Circle, Square, Triangle, L1(2) at the main menu. A message at the bottom of the screen will confirm correct code entry.
I Got The Power mode
Press L2, Circle, L2, Circle, L2, Circle at the main menu. A message at the bottom of the screen will confirm correct code entry. All characters in the game will have blue electrical energy flowing all over their bodies. It also seems to give your weapons more knockdown power.
Invincibility
Press L1, R1, L1, R1, L1, R1, L1, R1 at the main menu. A message at the bottom of the screen will confirm correct code entry.
Liquid metal textures
Press Square, Triangle, Circle, Square, Triangle, Circle at the main menu. A message at the bottom of the screen will confirm correct code entry.
Pin heads
Press Square, Circle, Triangle, Square, Circle, Triangle at the main menu. A message at the bottom of the screen will confirm correct code entry.
Small heads
Press L1(2), R1, L1 at the main menu. A message at the bottom of the screen will confirm correct code entry.
Unlimited ammunition
Press L2(4), L1, R1 at the main menu. A message at the bottom of the screen will confirm correct code entry.
Big heads...