Finally found out how to turn on god mode in xiii on pc. Another gamer posted on obscure site that he had interpreted some german cheats from another site. Follows is what must be done:
First you need a hex editor, such as hex workshop.
In the xiii system directory, open the engine.u file.
Search for the word God. The one you want is almost always the first found and it will be by itself with no other letters near it.
On the left side of the hex screen will be 47 6F 64.
With your cursor clicked at beginning of 47 on left window.
Now type 44 6F 67. In the right screen will appear Dog.
Save the file and agree to a backup also.
In game, as always hit F2 to open the console and type dog and hit enter.
A message at lower right of screen says God Mode On. To turn it off, type in dog again.
Having god mode on during a nightmare scene might have undesirable effects.