I had a momentary urge to recolor my water into milk for fun.
The tile set is quite large and experimenting with each asset can be very time consuming. So I haven't had time to address all of your pointers. I did spend some time working on the background and tried a few things.
1) I tried dimming down the stones to make them seem further recessed and darker. This attempt was more at showing only the highlights and insinuating the shape of the stones more than anything else. I was sort of worrying that the stones were looking a bit like beans for a while but I think it improved some as I dimmed it more.
2) This was my initial attempt at darkening the stones. I accomplished what I was going for, but ultimately felt like it wasn't far enough perhaps. The shadows and the highlights at this point had almost too much contrast division and it made them seem very much popping out--like bubbles.
3) I HAVE experimented with larger stones. This version was a prior attempt that I went back and finished coloring after you mentioned larger stones. I had basically come to the same conclusion before posting that maybe the background was too noisy and tried to blend the stones I had together. This created, to me, a sort of jigsaw puzzle like background that was strange in the shaping enough that it distracted my eyes from the more important elements that existed on the screen.
4) After tinkering for a few minutes trying to decide how I wanted to go about experimenting with new larger stones, I simply 2x scaled my existing stone tile. Honestly, if I were to go about redrawing new stones [larger] they would come out something very similar to this anyway, so why not?
Do any of these come closer to reaching a less noisy background that feels good? I look for references of backgrounds of this style and many of them seem to have very evident repeating patterns. That was a major reason I opted for smaller stones. It felt easier to hide the grid with smaller stones that intermingled more. The larger stones have much more recognizable shapes and patterns.
Thank you for the comment. Just to address the other things quickly before I have an edit ready, I have been strongly considering filling in the void with more stone. At least in a thicker pattern. Especially after doing the drop through floor, I really felt the need to bring a more visible division between the two. I will get on that, but it will take some time to fill all of my tile pieces in, so that might be a few days.
The surface level has been giving me trouble and I bounce between feeling like it looks good and feeling like it's too messy. I tried a few things in an attempt to go for what you suggested, but I guess I'm not skilled enough to just draw it without some kind of idea of what to go for. Im searching for references of things done similarly, but can't find many platformers that have used a sort of floor perspective like this(as of yet). [This is my next target area on revision though.]
Thanks again for the pointers.