Did some small run cycle. Could use a little tweaking, but it functions.
i made a basic brick pattern in photoshop, added noise, blurred the noise, then posterized it so it would have like 2 or 3 layers of grayness, overlayed it on the brick pattern, added lighting, then dithered it.
a tad bit more complicated than that though
-snip-
You could also index the color to transition the darkness a bit more to fit the style.
Image > Mode > Indexed Color
Edit: Actually never mind. The levels of color you used make it look like a smooth transition from the thumbnail. All indexing the color would accomplish would be restricting the color pallet.