During gameplay, press pause and enter a code.
Invisibility:
Hold L and press Up, Left, Right, Up, B, A.
All weapons:
Hold L and press Right, B, B, Y, B, A.
Slow motion:
Hold L and press Left, Down, Up, Right, B, A.
Fish-eye camera:
Hold L and press Left, Up, Right, Down, B, A.
