Damn dude, didn't scare me at first until the upside down long thing ran across the hallway! The upside down cross thing always unsettles me too. You did a good job setting the atmosphere here even with the harsh limitations of the GameBoy.
The only thing I'd recommend is adjusting the controls so that it turns smoothly when you press a turn key, I think it was like waiting for the usual delay before repeating like it does when you type.
Overall though, spooky level 9/10.