Nice organic compostition, maybe it even moves a bit too much for a background music. Also I think it is because of the tempo and the ryhtmic choices, but it feels more like a puzzle game music than a platformer one. The section at 1:36 to me is too static for a fast paced game like mario, and not very excited from a purely musical point of vue either. Still very nice job with the melodic cells development and the mood of the piece that is very underground compatible.