So I work in game audio. I have a masters in music composition, and beginner knowledge of coding just to add a few lines of audio-related code to my client's spaghetti code.

What you're asking for is not a simple task, and will certainly need AI or machine learning or something along those lines. You could more easily make something like this if its just a single melody with no other backing tracks (and there's plenty of software that does this), but to understand and distinguish separate instruments, including drums, hear them all as separate voices, and turn them into a whole other medium, is on a whole other stratosphere. If someone's going to make something like this, it's going to be made by a corporation and sold as a $1000 plugin.

But hey, at least it will most certainly be in C++, because that's the language of choice for most audio plugins.