Cool stuff. Something you can add is a torch for a side wall with light reclecting from that torch. I've never done tiles before, but what Stava said sounds like good advice.
Very good mockup! I really like the colors and atmosphere, really feels like a cave.
But I don't really like the cave walls, they're too repetitive, and the tiling is very obvious. A method I use to make sure tiling works properly is connect tiles to form a plus(+) shape, and then I can make sure it tiles properly from every side without making a obvious pattern. Also I'd suggest some cracks in ground if you are gonna keep it a plain color, to make it more convincing.
I like the style! The only issue I have is that the walls look abit busy, but that's just me.
This looks really awesome! I love your tilesets.