Not bad! The concept is neat, although it has some issues in practice.
I don't know the exact code behind stuff being visible or not, but sometimes you need to basically be like, exact on a ghost to see it. Considering they're pretty heavily damaging, that's rough.
Maybe some sort of feedback to the light would be nice as well; as is, stuff just pops out, but maybe having like, a cone of light in front of the character to help sell the whole "this is what the flash light sees", thing? And maybe combine that with making the area around that darker, I dunno.
I'm kind of armchair-deving at this point, so apologies. As a concept, I enjoyed this one! Would love to see it be built on, a bit more. Thank you for submitting it!