View All Cinematics:

 Start a game and pause it. Then  press  Right, Down, Down, Left, Down,
 Up, C, A, Left, Left. Now you can watch all the cinemas.

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To access these  hidden  levels, start a game and pause it.  Then enter
the following:

Production Team Level:

 Press Right, Down, Down, Left, C, Right, A, Z, Y.  You will then see a
 screen that says  "Heads Up!  Production Team Level." Now your enemies
 are the heads of the people who made the game.

The Horde Secret Level:

 Press Right, Down, Down, Left, B, Up, Down.

For the Corkscrew level:

 Press Right, Down, Down, Left, Start, C, Right, Up.

For the Undersea level:

 Press Right, Down, Down, Left, Start, Up, B

For the Offworld level:

 Right, Down, Down, Left, Right, A, C, Y, C, A, Right.

Trench Secret Level:

 press Right, Right, Down, Down.

Fade to Black Secret Level:

 Press X, Y, Z, Z, Y.

Chowder Secret Level:

 Press Y, Down, Down, Up, Right, C.

"One-hit wonder" mode: At the title screen, put the cursor on Game Start and press A, B, C, B, A, Start. You'll have no lives, and one hit will kill you.