IGMD is a subfolder of GameDataFolder, where the level logic is defined, chapter by chapter. If the contents of this folder are missing or corrupt, nothing interesting will ever happen :-) If you think your folder has been corrupted, download a .zip file of the unmodified files for your platform: Windows, Mac OS.
Notes on this folder
- The scripts in the subfolders of IGMD are files with the .bsl extension, written in BungieFrameWork Script Language. See BSL for more information.
- The level folder names are case-insensitive for Oni, so you can rename "EnvWarehouse" to "eNvwArEhOuSe" and you'll still be able to play CHAPTER 01 . TRIAL RUN.
- The Mac and PC scripts are almost identical, but there are minor differences in tctf_ii_cutscene.bsl and tctf2.bsl (boss battle of CHAPTER 13 . PHOENIX RISING): possibly an attempted bug fix.
- More generally, the Mac (and PC demo) version has fewer dev-and-debug features (a somewhat more finished product, perhaps...) but the missing BSL functionality prevents it from running some advanced scripts that Windows Oni can run. One problem is that the "global" folder is ignored, another is that a lot of preset commands are missing. This has been fixed to some extent through engine patching, see HERE.