Very solid work. It definitely creates a nice vibe.
I think the main thing I would improve here would be to work on the dynamics and articulations of the instrument. I've been thinking about either incorporating mix quality into a score called "overall execution," so that dynamics and articulations are more clearly articulated as an important element. I may also just make it its own category, though I guess I'm a little hesitant because part of what makes chiptune is its very mechanical sound.
But I think maybe that's part of the challenge of composing an orchestral piece. Great work.