Trial mode: Quickly press Up, Down, Down, Right, Right, Right, Left, Left, Left, Left, then hold Triangle and press Start at the "Press Start" menu for trial mode. This mode allows any level in the game to be played. The code must be entered before demonstration mode begins.

Max power mode: Quickly press L1, R2, L2, R2, L2, Triangle, Circle, Triangle, Circle, then hold L1 and press Start at the "Press Start" menu to unlock max power mode. Max power mode allows you to start with all weapons and unlimited ammunition. The code must be entered before demonstration mode begins.

Sudden death mode: Quickly press L2, R2, L2, R2, Circle, Triangle, Circle, Triangle, then hold L1 and press Start at the "Press Start" menu for sudden death mode. The code must be entered before demo mode begins. Sudden death mode allows opponents and your character to be killed with one hit. Or, Quickly press L2, R2, L2, R2, Triangle, Circle, Triangle, Circle, then hold L1 and press Start at the "Press Start" menu.

All multi-player characters: Quickly press Up, Down, Down, Right, Right, Right, Left, Left, Left, Left, then hold Circle and press Start at the "Press Start" menu. All the Bosses as well as the engineer and a few army characters will be unlocked in multi-player mode. Most of the Bosses have odd guns and may not be able to back up against walls or roll. Or complete the game under the easy and normal difficulty settings. The code must be entered before demo mode begins. After all characters are enabled, all of the middle row characters have special weapons (unlimited ammunition, but cannot place back toward wall), and Dan has a special pistol.

Max power, sudden death, trial modes: Complete the game on the hard difficulty setting to unlock max power, sudden death and trial modes.