Virtua Cop 2

Enable Big head mode
Finish the game in easy mode. When you are returned back to the
"Press Start Button" screen press X, A, Y, B, B, B, Up, Up, Up, Up, UP
on controller D. If the code is accepted, you should hear a sound.

Enable Mirror mode
Finish the game in normal mode. When you are returned back to the
"Press Start Button" screen press L, Left, L, Right, L, Down, L, Up, R,
Left, R, Right, R, Down, R, Up on controller D.
If the code is accepted, you should hear a sound.

Enable Random mode
Finish the game in normal mode. When you are returned back to the
"Press Start Button" screen press press B, Left, X, Y, X, Y, B, A, B, A,
Right, Left, Right, Left on controller D.
If the code is accepted, you should hear a sound.

Unlock Janet as playable character:
Begin a new game and choose a stage. While you are at the file screen,
hold Start until the mission startings.