Cheats:
At the game menu, type SS ADN, then type in these codes:
darkinv Invulnerability
darkpower Maximum power
dark20000 20,000 money
 

Mission select:
Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Using a text editor, edit the "shellcfg.h" file locacted in the "dark\shell\" directory. Change the "#define BTN_MISSION_COEFFICIENT 150" line to "#define BTN_MISSION_COEFFICIENT 157". The new "Cheat" icon in the lower left corner of the screen will allow any mission to be selected on the dial.

Hidden level:
Play the Death Blow level by clicking on the spiral at the level selection screen after completing level twelve