Thank you for the in-depth review man. I really appreciate it. :D
For this soundtrack I really mostly only used my own JSFX. But I've made them all availabe. You can find 'em all here if you want to take them for a spin: https://github.com/JoepVanlier/JSFX#installation-instructions
They're all free. Beware though, I can't guarantee that they'll be completely bug free, but if you find any bugs, let me know and I will at least try to fix them.
The ambient opener makes a lot of use of Swellotron in particular. It's an effect that takes two sound sources and turns them into ambient washes. It's basically kind of like a vocoder and reverb in one. It takes two inputs, computes their frequency dependent energy over time and adds that in a buffer (a reverb tank basically) to decay over time. It resynthesizes this with random phases which makes the sounds very wide (because left and right are not correlated). It's not the best for live use because it has quite a bit of latency, but it can be really nice for creating some audio washes for resampling later. I have a short tutorial of it here:
The synths are typically Yutani in paraphonic mode. In most polysynths, you have a filter per voice. In paraphonic synths, all the voices go to the same filter. With non-linear filters, this creates a kind of unusual distortion which I quite like. It makes it sound kinda old.
The strange synth in track 5 is Yutani again with audio rate modulation on the filter at very high resonance. It's a particular filter with some non-linearity in its feedback path, which causes some unusual effects as you can hear. Personally, (also based on feedback received), I think I should've maybe made it slightly less harsh to blend in a little better.
I'll probably do some touch-ups on the tracks based on the feedback I've received and then maybe put an updated version here (and maybe on bandcamp). Unfortunately I had to work the week of the compo, so I was a little strapped for time trying to get it all finished. :D
Thanks again for the feedback :)