I really like the sprite work it's very cute and cohesive. the music is quite fitting as well. the rooms have decent challenge and thought put into them. I like that the shooting is tied to the health to encourage strategizing, I liked gathering up the skeletons so that I could jump over them all to avoid shooting them haha!
The lighting effect is very nice and I like how the magic bullets have lighting on them to act as an additional light source, that's a neat idea and could be helpful, however I was trying to avoid using it as a light to preserve health so it went largely unused as a feature of me, but I appreciate you have placed some light sources in the environment as well as the souls also having lighting to them to for better navigation.
While I do like how clear the theming is with everything, from unlocking doors, shooting enemies, shooting as a light source, all tied to costing your health, it makes the game feel like it requires absolute perfection with no room for mistakes. if this is intended as a rage platformer, then that's quite a unique way to provide that kind of challenge, if it's not though I'd tone it down a bit, like maybe having different costs to the health from different uses like for example, it costs less to just fire as a light source, more when you hit an enemy etc.
I do also like the detail of the area of vision reducing based on your health, that's a good diegetic indicator of your health! however I think it gets reduced so much to a point that I can't see anything and it's not wise to shoot as a light source because then I would die I felt, so it made the game much more challenging than it should have imo.
With this difficulty it felt quite punishing to have to restart the whole game over each time you die, I would suggest having save points per room.
Overall pretty good game through, Great Work!