Locate the bookstore window that has the book on the Holy Grail. Look in the window next to the door to see Jane Jensen, the woman that developed the Gabriel Knight series of games. Additionally, examine the book that Gabriel authored about the Voodoo Murders. Gabriel will say "Wow, isn't he some famous author or something?"
Press [Shift][Strg][~] and a window appears. Now type in:
and a file !!!Readme.txt will be copied to your GK3 directory. You should read this!
With the console you can extract all files (sound, graphics, animations...), activate eastereggs, Create places and animations, etc.
To activate the eastereggs type:
In the game an egg appears at the person or place, an almost completelist of eastereggs is supplied with the readme file.