Really like the idea! I found the collisions to be a bit tricky, sometimes it felt like I was pointing my light straight at the little demons and they still just walked right through it and got to me. My hitbox also felt a little larger than I expected at times.
Feels like the game could benefit from a few screens ramping up the difficulty (i.e. less and slower demons), before getting to what is currently in place.
I like how you integrated the gameboy itself into the gameplay, and it definitely hits the marks for spooky!
Great job!