bodhi: It's actually neither sprites nor BOBs! As I wrote in the scroller, I still haven't got everything figured out, blitter is one of those things. So the background effect is a pure CPU thing. I have a small 20x16 buffer where I do the effect, "chunky" style and then I simply use the CPU to map each of these 3200 bytes to a 16x16 pixel tile that I write into a bitplane.