Make it so it has rotten tumours sprouting out in every area. Make it more fleshy.
Make it so that it in in an advanced stage of decomposition, you may partially see bones and organs hanging from the growths.
Do you have discord? If so, friend me as “Lv100DominusUltimus#4144”. I could send you better feedback there. I am afraid unintentionally breaking any rules by posting images or graphic descriptions here.
When I make horror games I think of things that would scare me, In matters like this do the same and think of what would scare you If you seen it, of course doing that would also be good for mechanics of the creature.
What if stuf fluke darkness scares me. Thats a while new game idea there. Its just a map where you cant see where your going. Noises . Maybe eyes ,Mirrors. This really sparked my brain thank you!