Open the "gothic.ini" file in the game folder and replace the "test mode 0" entry by "test mode 1". Then, during the game, press one of the following keys:
Display console: F2
Window mode: F3
Normal mode: F4
Fixed camera view: F5
Floating camera view: F6
Cycle through game sections: F7
Full health and mana: F8
Get injured: H
Spin around: Z
Drop into ground: K