Thankyou for playing my game! Music does play, but only as you get injured / lose sanity - until then its just ambience to help reinforce the jam's theme. As for the invisible fellas, They have a very unique interaction with light sources - they actually receive hitstun as you shed light on them, and they hide their footstep hurt boxes underneath the player when they get to your position. I think I make more unique sfx for taking damage will make this more clear in the future.