Along with Flying Flame, this game has the best-looking lighting I've encountered so far. Good job! I also liked the themes of sacrificing your character into the network of light and carrying on despite the deaths.
My character's lighting was glitchy when fading in (causing tiles around the character to have a random brightness) and at the end, I was dead but I also had won and I pressed Z a dozen times until it stopped telling me I was dead and got me to the ending screen. Other than that, it ran smoothly.
About the thing with players being able to see too much if they have their brightness up, I guess you can make every tile (other than the one the player is on) completely invisible until there's a light source nearby. Maybe this can be done with light masks, or maybe you can just set their tint or opacity manually.