This is a brief description of the principles I employed making the music for Brink of Extinction.
Before I even set about composing anything, I started digging through the sound libraries I had at the time. I use East West Pianos Gold, EW Symphonic Orchestra Gold, Stormdrum and some other EW libraries. I quickly found that these alone would push the music too much towards a symphonic sound that I didn't want. So I set about founding some good, free VST:s and settled for STS-24, T-Force Alpha and Brzoza.
The EW-products and free VST:s are generally used the same way for the entire OST. Brzoza mainly for bass, STS-24 for pads and T-Force for the melodies and as complementary bass. I use EW symphonic orchestra to overlay the more digital sounding pads and Stormdrum for... well, drums. Although the OST in general has a very cold and techy sound to it, I also use pianos on many of the songs, choirs in the main theme and another one of the tracks and violins in several places. I find these become nice details that add a much needed touch of real instrumentation to the songs.
As for composition, most of the songs on the OST are of a more conventional structure. Only the two show room songs and achievement display area song are loops, the other ones have a start and a finish the way most "normal" music has. As such, the songs tend to begin with an intro/verse that leads into a chorus of sorts, then back to a verse. Much of the music stays around one main chord, giving the music a sort of stable feel that doesn't require too much attention. As such chord and melody changes are sparse and mainly used as effects to add depth to the songs in specific places. A common chord progression is going from Bm to G for example, which I find very effectful as the notes in Bm, B D and F# complement the notes in G - G, B D - very well. Playing a melody in Bm over a G, makes the chord Gmaj7, which can sound very powerful.
Another effect I use is to overlay a melody with another halfway into a solo. This is basically a homage to bands like Thin Lizzy and various melodic metal bands that tend to play guitar solos with a terse overlaid. Difference here is, I do so with synths. :)
I also use a lot of pitch shifting, primarily on the bass. This is an effective way to not only add a bit of depth before significant changes in the song, say before a chorus, but also to add structure by making a pitch drop every 4th round of the bass line. Pitch change is also used for the T-Force alpha melodies, but then usually via the automatic portamento function, sounding a bit like a slide guitar! :D
The drums on the OST are generally very simple, mainly a constant pulse beat and maybe a snare, bass drum and hi hat with a low resonance filter. Overall, resonance filters and other filters are very common on the OST.
Lastly, I master the sound track using TDR slick EQ, Molot and Limiter no 6 to ensure that the volumes are kept on a good level and even and that the sound is the way I like it.
Because I can't upload the sound files here and they have yet to be released on streaming services (fairly soon though) I can only point you towards the game and to these videos so you can hear the result of what I have described above. :)
Questions and comments are welcome.