GameDataFolder (commonly called GDF to save on typing) is a subfolder of the main Oni folder.
It holds the following:
Below we list the instance files in parallel with the folders (subfolders of IGMD) which hold the corresponding level logic.
SPOILER WARNING: The "Chapter" column links to summaries and analyses of Oni's storyline.
||level logic folder
The level0_Final instance file is only loaded once, when Oni starts.
IGMD\global\ is not present by default, but if it is created, the functions in any scripts placed inside it will be accessible from all levels; however, the PC demo engine ignores the global folder.
RAD Game Tools, the makers of the Bink video format, offer standalone apps for all platforms if you want to watch the .bik files on their own. The movie files are not needed for Oni to run. You can thus rename or move intro.bik out of GameDataFolder so Oni starts faster.
How Oni finds its GameDataFolder
In Windows, Oni's engine first looks up GDF in the working directory (a.k.a. "."). If ".\GameDataFolder" is missing, Oni tries parent folders all the way up to the root (e.g., it looks for "C:\Program Files\Oni\GameDataFolder", then "C:\Program Files\GameDataFolder", then "C:\GameDataFolder"). As a last resort, it looks for ".\OniEngine\GameDataFolder" the same way.
The Mac Oni app follows the same search pattern for GameDataFolder/, but does not look for OniEngine/GameDataFolder/.