Invincibility
For invincibility, press Option 2 during the game to display the "Bomb Parts" screen while not standing next to a monitor. Press Up, Right, Up, Left, then Down. You will hear a sound if the code was entered correctly. Repeat this code to return to normal.
Weapon Power-up
For a weapon power-up, press Option 2 during the game to display the "Bomb Parts" screen while not standing next to a monitor. Press Down, Down, Down, Down, Right, Up, then Option 2 to set all weapons to full. This code may be repeated as needed.
Level Select
For a level select, press Option 2 during the game while standing next to a monitor. Press Down, Up, Up, Up, Up, Up, then Right. You will hear a sound if the code was entered correctly. A level number will also be seen in the bottom right corner of the screen. Press Up or Down to change this level number. Pressing Up or Down will also toggle the score from "00000" to "00128" to indicate whether the starting location within the level will be the beginning or the end. Press Option 2 to start playing at the indicated level.