Chessboard effect
An endless checkered pattern rotating, zooming or receding in perspective — a demoscene staple since the late 80s.
It comes in two main flavours. The flat one rotates and scales a grid across the whole screen, effectively a rotozoomer with the simplest texture imaginable. The perspective one lays the squares out as a floor running to the horizon, often with a sine wave or colour cycling along the rows. On the Amiga and C64 it was usually built with clever tricks — precalculated lines, bitplane manipulation or per-line copper colours — rather than by drawing every pixel.
Two colours is as minimal as an effect gets, yet it is hard to make look good: edges go jagged and aliasing shows immediately as the squares shrink toward the horizon. Which is why it never quite died.