I have a playlist I use as background music for our Through the Breach sessions. It’s not atmosphere in the sense of just creepy noises, but it is meant for ambiance. It began as mostly ragtime and early New Orleans jazz, which is a bit anachronistic, but popular music from 1890-1910 has not survived well and is rarely performed in modern times. There’s some tin pan alley stuff, but the jazz element is mostly WW1 – late 20s (sometimes in original period recordings, but also more recent versions).
From there, I expanded it to fit the other Malifaux aesthetics such as:
1) A few selected classical tracks and waltzes, to represent higher social-economic environments.
2) Some western-themed songs. Admittedly, most of it is spaghetti western tracks, but there’s some folk music too.
3) Music from similar themed entertainment, such as the Penny Dreadful and Carnival Row soundtracks.
The result is fairly eclectic, and I go back and forth on whether the authenticity of the early recordings outweighs their sometimes questionable sound quality, but I do find it to be a nice touch to the atmosphere, and fairly unobtrusive if your group is used to background music already (as ours is).
If you’re looking for Malifaux-themed background music, check it out. And I’m always looking to add tracks, so let me know of any good suggestions!