Cheat List
Enter the following during the middle of gameplay:
Y, A, B, X, X, L - shotgun
Y, A, B, X, X, LEFT - invisibility
Y, A, B, X, X, RIGHT - slow motion
Y, A, B, X, X, DOWN - fast motion
Y, A, B, X, A, R - change spawn point
Y, A, B, X, A, RIGHT - infinite ammo
Y, A, B, X, A, DOWN - max charisma
Y, A, B, X, A, LEFT - nail gun
Y, A, B, X, Y, R - sub machine gun
Y, A, B, X, Y, RIGHT - sniper rifle
Y, A, B, X, Y, LEFT - rocket launcher
Y, A, B, X, Y, DOWN- heavy machine gun
Y, A, B, X, B, L - ragdolls

Unlock Liberty Island
To unlock the extra stage, Liberty Island, just beat the game on any difficulty