Wow this is fantastic! One thing I'd suggest is adding some kind of indicator (or passive upgrade) that points to the closest torch. I definitely struggled to find ones that were lit sometimes.
A million years ago I started a game called Darkness Sleeps which is kind of the opposite of your idea. If you move into the darkness you plant a torch and too much light summons the final boss faster. I should get back to that some day :) https://twitter.com/ben_burnes/status/1557856229824704512