One of my friends wrote Numula, a Python library for generating music with nuance. It permits subtle adjustments in dynamics, timing, articulation, etc. to mimic human play more closely. Below is some sample output, the third movement of the Appassionata sonata. It sounds much more natural than typical conversions of classical piano scores to MIDI.

https://www.youtube.com/watch?v=gQQoDCtSfeU https://github.com/davidpanderson/Numula/wiki