I think the large sandstone bricks look too wiggly; if you remove the bezel decoration on the front, they could easily pass as compacted snow-bricks. The black shadow also looks like it's too far forward, if you were going for a backlighting effect, so it ends up looking a little out of place.
Im not gonna redesign the large bricks. atleast not yet.
The pyramid interior could benefit from some more contrast in the palette, the shadowed color is too bright and it makes the entire scene look flat, and like with the bricks, the black shadow on the pedestals is too far forward and looks out of place; all you need to do is push it farther to the right (almost up against the edge) and it'll look fine.
i couldnt find a better colour palette for this right now so until i do, it stays as it is right now. (though the standing torches did get that shadow edit)
I really dig that nighttime scene; that horizon looks like it could strongly benefit from some the silhouette of some sandy hills against the gradient, not unlike the shape that's right above the water in the oasis scene. I might be wrong, but it seems like a neat thing to try out; you could also use it to hide the artifacting caused by the gradient tiles running into the diagonal sand tiles.
lazy patch at the edge of the pyramid. ill most likely just end the bg with a block, not a slope in practical use. i might do the hills idea here too though.
The volcano environment looks neat too, but you may want to consider scrapping the purple haze, since you're going to run into more cut-out artifacting as foreground objects need to be placed overtop of it, unless you can come up with some creative way to mask it, of course.
you mean like this?
I hope this criticism doesn't sound too negative; I really am enjoying all of the art you're posting so far.
its helping though.