CheatMode:
----------
Press Left Shift + F11 then type the Codes:

Code Result
--------------------
timeless - Stop Time
fidel castro - View Dialogs
medic - View Hints
powerman - New Weapon
schneider - End Current Level
clint - Win Current Level
jackal - Ammo
hollow man - Invisibility
show me all - Show All Objects
zeus - Help From the Gods

HeXcheat:
---------
Go into Desperados\Game\Data\Savegame folder and use a
hex editor to open Profiles file.
Number on hex offset 000014 represents current level
decreased by 1.

Example: value 0F hex = 15 dec, which means that you're
on level 16. The maximum value this byte may be set to
is hex 18 (for Level 25).