At the main menu, hold LT + RT and press Down, B, Up, X, Down(2), Up(2). Release LT + RT and a Cheat option will appear at the main menu. Select the Cheat option, then enter one of the following case-sensitive codes to activate the corresponding cheat function:

Get Machine Gun
Enter KKcapone as a code.

Get Revolver
Enter KKtigun as a code.

Invincibility
Enter 8wonder as a code.

One-hit kills
Enter GrosBras as a code.

Full ammunition
Enter KK 999 mun as a code.

Level select
Enter KKst0ry as a code. Note: This code includes the number 0.

Infinite spears
Enter lance 1nf as a code. Note: This code includes the number 1.

Get Shotgun
Enter KKsh0tgun as a code. Note: This code includes the number 0.

Get Sniper Rifle
Enter KKsn1per as a code. Note: This code includes the number 1.

Bonuses completed
Enter KKmuseum as a code.