At some point in the game you need
to open a box using a code that comes with the original packaging of the game.
In ODG that code is hidden, written on the back of
the
front cover.
You actually need to remove the cover from the DVD case to solve the puzzle!
The clues can lead you there if you can think “outside the box”, but there’s
also
Martin’s
notes that make things more clear. In a nutshell, you need to solve a puzzle
outside the game! CS does
not come in
a
DVD
case,
and
there was actually no place to hide the code, so it just comes written on a
piece of paper.

On a side-note, all walkthroughs
posted on the internet that mention the code itself should have it removed,
cause this way, this clever, old Sierra-like copy protection is
rendered
useless.