What would you call the genre of this song? It is common in a handful of indie games

I’d call it a mix of jazz and trip hop.

Instrumental trip-hop.

chiptune dreampop

Ineffably awesome video-game, art out there... magnificent... No words...

Your question is quite a challenge, indeed! The soundscape sounds like a set of different genres in chiptune-like lo-fi jazz fusion sound, including soul jazz, chillwave, future-garage, nu-disco, and I also hear some noir notes if feels like...