This sounds incredible for sticking to the limitations that the original OST had. I like the melodic development through the piece, and the rhythm is really satisfying! The entire piece has a very strong sense of forward movement too.
Some parts of the melody and harmony do sound a little bit like sonic music, which detracts a little from the whole underground theme. I think with a little more bass presence this would fit really well.
Overall really great sounding composition, well done!