Use the following trick to unlock all the levels in
the campaign mode. Note: This procedure involves editing a game
file; create a backup copy of the file before proceeding. Use
a text editor to edit the "*.usr" file in the folder
with the profile and save game directories. The *.usr file contains
information about the missions and other game options. You will
find some lines like this:
*VARIANT 1 0
*VARIANT 2 0
*VARIANT 3 0
The first number is the difficulty of the stage, while the second
one describes its completion. To unlock all the levels, edit the
lines to resemble:
*VARIANT 1 1
*VARIANT 2 1
*VARIANT 3 1