The stones are really sticking out, the no block outline really makes it seem out of place.
the stones on the cliffs or the little piles on the platforms?
I don't know why so many people aren't feeling the highlights along the edges, it's pretty standard practice for the edges of walls in platformers to be lighter than the center, sometimes completely black in the center.
I edited the roofs as faceless suggested, and I faded out the back layers with a bluish tint:

I also made the top line of the platforms straight. I think the highlights definitely need to go on the top, but I can keep them on the other sides (maybe lose the yellow?) I made the top line perfectly straight as an effort to make the edge less discernible
edit-
Adarias, I think the darker patches makes it look too busy in spots compared to the empty plain areas, I might do something similar down the road, though probably not as prominent