Dynamic music.

Long ago i suggested that faster paced music be played while a player is quickly blasting through a zone. After thinking about further what i really want is music that responds to the player, not just a zone default background.
I found this today and think it highlights pretty well what im talking about, and how other game developers handle dynamic music: https://www.youtube.com/watch?v=7X3LbZAxRPE
What i personally suggest is that for each composed song, 2 or 3 deviations are also composed. Each which correspond to 1 of three emotions: creepiness/awe (the default for the zone played when not much is happening), thrill (faster more and more metal for when massive damage is being dealt), and immediate danger(for exceptionally dense rooms and boss fights). Then simply link the actions of the player with a sound manager which transitions the music into the corresponding tone so as they align with the players current experience.
ps you might also want a transition verse for each possible change in music so as not to jar the listener.

It seems like a nice idea, but you gotta keep in mind that 70-90% of zones are usually 'action' of some sort (besides towns). It works with games like doom where there's clear breaks between action and suspense/rest, but the music would be transitioning way too frequently in poe.