ShellShock [PSX]

Cheat Menu
At the title screen, enter the following:
Up, Down, Left, Right, Down, Down, Right, Right, Square.
The screen will change to a photo of the game characters with a cheat menu below.

Debug mode:
Press Up, Down, Left, Right, Down(2), Right(2), Square when the Core Design copyright screen appears in the NTSC version of the game. For the PAL version of the game, press Triangle instead of Square. A debug menu will appear with the following options:

Play any level.
Run a CD test.
Play the game with maximum firepower.
View the FMV sequences.
View the credits.
Start a sound test.

For an additional bonus, highlight the credits option in the debug menu and press Left(8), Triangle.

Invincibility
Immediately after starting a game, abort it and when you return to the title screen, enter:
Up, Up, Up, Down, Down, Right, Right, Triangle.

"Payback" mission:
Enter the briefing area and locate the locker on the left side of the screen Open the locker and enter 4L2CZCQKDAABACQDB at the password screen. A mission to destroy the Crimson Blade training camp in the Masirah Mountains will begin.