Could the octagons perhaps not be the entire wall structure? I know that would involve losing some of the work done already, but I think I'm not the only one who isn't really feeling this tileset at the moment. They could be enclosed in something else, or disconnected from the actual floor, or just only a wall texture while a dedicated platform rests on top of them with some perspective. For example, dropping the "elemental temple" but keeping the "ruin" and "space" ideas, it would be kind of cool to stick a street platform on top of those octagons and make it a series of asteroid-like bits of blasted apart cityscape floating through space. One way or another, though, I think the walls need to be a little more than just this single texture.

(in case the Nature's Ruins discussion continues for whatever reason, I didn't mean to say that it's unbeatable -- it has problems, and it can be surpassed -- but this particular tileset is not currently on track to be the one to surpass it.)