I love the foreground but the background confuses my eyes a little. Not quite sure why...

Edit: I think it's because the background should feel like a *wall*, which means there wouldn't be stalactites as much as large pillars or something else that's tall?

Sorry I haven't commented yet.  I really love the edge pieces, especially on the latest one where they've got the proper contrast with the forground.  The darker forground worked a lot better, it had better visual priorities.  These new walls don't quite work yet, I think the random elements worked a lot better but if you just incorporate them into the new tiles it'll be an improvement for both. You've got good volume on the individual rocks but the shapes are too uniform and don't overlap making it look flat.  Break up the lines a bit like you did with the slope edges and it'll look a lot more visually interesting and organic.  You've made some daring choices with the colors but it works surprisingly well.  I really like this set so far, I look forward to seeing more of it!

Yep, I love the new background, though it is somewhat repetitive. Maybe like Sharm said, the background needs more organic shapes?

The backround is good as it is as long as you make edges for it , the only reason it doesn't look good now is coz you can't see all the assets normally in a finised tileset.

Mumu, you're right. I don't care at all about repetition when there's interesting stuff to look at elsewhere!

Not sure I like the bluish area. (Unless it's supposed to represent the outside sky?) I think it would look good to do something quite a bit darker.

Aha! That's *exactly* what it needed. That's fantastic.

You can always make it look even lagrer if you use Parallax scrolling .