Gothic 2 NotR versions:
You need the so-called Report Version of Gothic 2. But note: Due to incompatible naming conventions you will probably have no sound and no subtitles in your original Gothic 2 after installing this patch. To fix this problem do the following:
The modification itself:
You probably need the Full Velaya Installer from worldofgothic.com. If you happen to already have the German version installed, however, you only need the smaller patch.
German voice output
To hear German voices in the Game download Velaya_Speech.exe (German).
If you speak German, make sure to check out the German page for more downloads.