These are great soundtracks, and what I like very much about them as well is that I haven't heard anything like these before in TDM. Many of these tunes remind me in particular of this ambience - Dark Ambient Music #4 Void (and also #6: Dreaming of Nowhere and #5: Lost Tape). It's one of the more haunting styles, in my opinion.
While listening to the ambients I made soundshaders for them so they can be tried out ingame. They'll show up in the DarkRadiant editor in the ambients list, all starting with gast_. It should go into the /darkmod/sound folder (create if necessary), and it's actually a .txt file that was renamed to .sndshd, so can be opened in the .txt editor. The sound files themselves should go into the /darkmod/sound/ambient/ambience folder.
Dropbox - gast_ambients.sndshd
It's very straightforward to make soundshaders, just copy-paste an old one and replace the ambient name and the filename. Here's a template:
Edited by Dragofer, 15 July 2015 - 07:03 AM.