I saw recently how intriguing a silhouette pxart can be, so I decide to try one myself.
I didn't fancy dithering background, so I asked GIMP to do it for me.
You could add another layer of machinery in the background, but that would spoil those shadows.
The story I imagined for this is as follows:
Ferrona is an artificial planet, which means it has no bottom. Basically you can fall through the middle (if you do not crash on any pipe before).
While new parts are build outside, the middle gets forgotten. Unused machinery and rusting environment show a long and stormy history of it's civilization. Today no Ferronian knows old parts, what's lurking under your feet. They are constantly building upwards as if escaping something unknown.
If I find a courage to write a book someday, it will contain adventures of 4 space-time travellers there. And everywhere.