We are well within the theme, very sober and very neutral 8-bit instrumental. Times of silence, atonal passages (just after parallel 6ths, which contrasts even more).
But I find that it lacks a bit of overall direction, the unstructured melodies stick well to the theme, but almost only that for sometimes +10s, it's perhaps a bit much ^^' (afterwards it may be a choice assumed, and it fits well with the underground atmosphere)