At the title screen, hold R and rotate the D-pad clockwise until 7 splashes of blood appear on the screen. This will allow you to see blood when you shoot someone in the game.
5/26/2001
Stage Select
Pause the game and press:
L, A, Up, Down, R, Up
The passcode box on the screen will change to read: #PWR to indicate that the code is in place. While the game is still paused, press and hold B to get the level select to appear in the password box. With B still being held, press Up or Down to choose a stage, then release B to warp there.
12/2/2004
Debug Mode
Press P to pause game play. Then, press LS, A, Up, Down, RS, Up to activate debug mode. The last three letters of the password will change to PWR to confirm correct code entry. Press B + Up or B + Down to scroll through the levels and screens, which will appear in the password box. VRGN 1 through VRGN 5 are five secret Doom-like levels that are modeled after the interior of Virgin Studios.