I'll start off with Raiden II's Repeated Tragedy.
A local restaurant had this game, and every time we went, I'd beg my parents for money so that I could play it. I wasn't very good at the game, so I never got past the first stage, and so I heard this song a lot. Really gives me nostalgia.
Also got to shout out Streets, from Timesplitters too. I put a lot of time into this game as a kid, and this song is what got me into futurepop (love me some VNV Nation).
I stumbled on the OST for the unreleased Jazz Jackrabbit 3 recently, and I keep playing this track every now and again, it's such a banger. This whole subgenre from Epic Games' early efforts (and stuff those composers did for other companies) is really cool, I with there more games beyond the Unreals and Deus Ex with that style. This track from Unreal 2 is another great one
The cut Downtown theme from Vampire: the Masquerade - Bloodlines, it's just such a vibe
Fertile Rondo from Bayonetta 3 is also just
, great 5th Element vibes
Brain Freeze from Yuri's Revenge, I miss the "just stick some old movie/TV quotes in" era of electronic music
This track from Descent (this particular recording off a Roland SC-55, I'm pretty sure I originally found it on youtube but it seems like that upload may have been taken down, and a lot of the other ones I could find don't sound as good)
The whole Neotokyo soundtrack really, just an absolute masterpiece composed for a free mod for some reason. Some standouts: Beacon, Imbrium, Tachi, I just absolutely love the combination of more electronic sounds with strings and piano in a lot of these.
On the more ambient side of things, STALKER has some great ones, Call of Pripyat especially, like the Pripyat theme
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