Very interesting take on the theme, and I really liked the artwork and isometric environment. I liked that you need to sacrifice more of your health to reveal more of the environment, but I often felt unsure of whether or not there was more map to load in because of how long you had to hold down the "glow" button for. Maybe a subtle outline of the extent of the map that the player can always see would be helpful, and then holding the glow button just adds in more and more detail.
I also think the flying creatures could do something a bit different, or be taken away entirely, since they create the same tension for holding down the glow button for too long - maybe the health should just always deplete a lot faster as the map is revealed more.
Really cool mechanic, and very appealing game. Well done!