Skip Mission:
     Requires the v1.33 patch. During play press Ctrl+Alt+Shift+End.

Level select: 
     Requires the v1.33 patch. Note: This procedure involves editing a
game  file. If you don't know what you're doing, don't try this. Use a
text editor to edit the "dark.cfg" file in the game directory. Add the
line "starting_mission". Now select the "New Game" option to play that
level.

More Money:
     Require  the v1.33 patch. Note: This procedure involves editing a
game  file. If you don't know what you're doing, don't try this. Use a
text editor to edit the "dark.cfg" file in the game directory. Add the
line  "cash_bonus". When you start, you'll find that you've got plenty
of dough.