I think you did the right call, the sound and music was more essential to the game than the graphics. In the first half I read the subtitles but after that I tilted the display of my laptop (to not see it) and just listened. Maybe some simple but nice graphics/animation like in Fish in the Dark would fit here as well? (With an option to show just that, nothing else.) I noticed it made me kind of zone out and listen more. Just a suggestion, I've been thinking about using vague backgrounds in my entry as well (on a game I scratched) but I'll do this instead next time, I think.