I think his point might be that the level of overdraw with this scaled 2d sprite solution is expensive. The CPU costing model for PICO8's scaled sprite (sspr) function is 2*n (n = number of pixels drawn). So drawing something the size of the screen once is 32k cycles, which is 0.4% of the CPU budget for the frame. Let's say 32 full sized layers, that's still only 8% of CPU budget, so ... yes I agree this doesn't seem expensive even via brute force with no tricks. :)