Nice entry !

The ostinato at the beginning is very effective.

And when you double the strings at the octave at 1'55" it adds intensity.

And if I may ask, at 38", instead of raising the ostinato by a third and staying in the same scale, you could raise your whole piece (bass and guitar included) by a minor third. You go from an A minor to a C minor. It has a dramatic, cinematic feel.

Otherwise, well done for the chromatic rise on the piano, you've validated all the notes!