This new series is getting off to a great start with this creative tangent: video game music to work to. Allen K. builds on that previous note:
I will second your reader’s use of classical music from video games. I got started with the descriptively titled, “Epic Legendary Intense Massive Heroic Vengeful Dramatic Music Mix - 1 Hour Long.” But to give you an idea of how vast a library YouTube is of such stuff, check out this playlist.
For a more directed recommendation, I’ve found modern cello to be particularly fruitful (even if not used in a video game), especially by Zoe Keating—e.g. “Sun Will Set” and “Tetrishead”—and in the same vein, Julia Kent’s “Barajas.” Those three are really beautiful cello pieces. Do check them out, even if you don’t spend days researching the epic mixes above.