To get quick and easy kill's all ya gotta do is jump up on top off a few box's wait for da enemy to walk past then hold l1 and wait for it to red and hit the action button and bang you will jump off the boxes and kill the enemy right away. (You can only do this with a weapon in ur hand) HAPPY KILLING
Insert the following password at the main menu: Up, Down, Left, Right, Up, Down, Left, Right.
Insert the following code on the game's title screen: Up, Up, Down, Down, Left, Right, Left, Right.
To unlock a bonus level where you play not as Daniel, but as Leo, you must complete the game once through. Thereafter, this mission will become playable.
Relive Scene Option
Successfully complete the game, which will unlock the "Relive Scene" option. This will allow you to go back and play any mission over again.