I really like this.  Especially the floor.

My only suggestion would be to spread the green moss around a little more.  Maybe use dithering to make it fainter over the walls and wooden beams?

btw, I'm now seeing this on my PC and I can see a BG wall and it all reads better. Earlier I was on Macs :/

I can see the hole but it is fairly hard to read, you might want to darken up the planks in the hole, maybe get rid of the highlights on it completely.

I really like the style of everything else though, beautiful!

yeah, its not reading like that to me, I see stairs :/

Maybe the horizontal beams could be skewed, or broken so its reads clearly as a non playable area?

 You see stairs? Its a hole, the inner wall with wood planks is the background. The rock sides is another layer.

I like these tiles a lot.

My only comment is that if those are stairs the player can desend then maybe the tops should be highlighted so it reads as active. I am 'reading' this because the sides are fully lit. If this is not an area the player can desend then the sides should maybe fade to dark so it reads as closed.