Thanks for the suggestions!
And yup there is an ending, it's around 50 rooms in.
Only 50 rooms? I thought I’d explored more than 70… I guess I’m just really slow. Or maybe you mean “50 consecutive rooms without getting caught by the shadow”? In that case, actually, it did catch me at least 3 or 4 times—if the room count resets when you get caught, I don’t think I ever made it past 20 rooms T_T