I know I'm not really part of this project, but I like to give my opinion now and then. Can't wait to play the finished product.
Anyway, in my opinion, that "spooky nothingness" is actually much scarier than blood and gore, because you're always expecting something to jump out at you when there's actually nothing at all. You can also try to use both and balance them out. Think of the System Shock games, especially the second one: there's plenty of enemies and corpses and blood, but there's also a fair share of empty offices and hallways with nothing but furniture and those chilling audio logs in them.
And about the furniture tilesets thing, I think that there's no suitable furniture tilesets out there. It's a lab, so the furniture has to be just like the equipment: metal, sterilized, simply practical instead of being aesthetically pleasing or comfortable.
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