I like to listen to the genres Synthwave and Dark Ambiance. Spotify is pretty good to find new music in that regard. Since you asked for artist recommendations and not genres:

Judge Bitch – their Album Horse Blood is pretty good.

Perturbator – sounds like you're driving on some rainy highway at night to your cyberpunk destination

There's also Instrumental Nu Metal, for example:

Andromeda – start with their song Synthesis

MASTER BOOT RECORD – it's just riffs and booms, usually no vocals

A. Yarmak – has some nice metal remixes, for example Hydrogen from the game Hotline Miami

Then there's Dubstep and Breakbeat, for example:

The Prodigy – uses samples heavily, but also has a few tracks without spoken words

Lindsey Stirling – Dubstep and violin, interesting combination.

videogame OST […] either really well known or fall into the orchestral and/or “epic music score” I’m not looking for

Well, there are tons of videogames and many of them don't have an orchestral/epic soundtrack, and even more of them are not very well known. I think you're limiting yourself here.