Regruntled.com

Here is another Patchwork sudoku, except that the graphics are moving. The images in the cells are moving in a two-dimensional random walk. Normally we think of a point moving relative to a fixed background (a drunk staggering around a lamp post is the classic illustration). Here the drunk is standing still and the landscape is moving underneath him.

For you math trivia buffs, Brownian motion is a three-dimensional random walk. In two dimensions (and one dimensions), random walks exhibit recurrence; a randomly staggering drunk will eventually return to the lamp post. In three or more dimensions, the random walk may or may not return to the starting point.