I think it would be really cool if there were haunted portraits or mirrors. Maybe a toy level where the dolls changed positions. You could throw some Easter eggs/references to other horror games and movies. Or interactable objects like if you flip a light switch, leave the room and come back, and the light bulbs a different color. :) I did a similar game Haunted Realtor for last years jam if you want to look! (Not nearly as detailed as ur game tho)