According to Wikipedia:
"In mathematics, the term chaos game originally referred to a method of creating a fractal, using a polygon and an initial point selected at random inside it"
As an explanation check out this cool youtube video by Numberphile!
In this video they make a triangle and then use any "trace point" which iteratively moves from its previous position half way towards a randomly chosen point from the original triangle. This process results in a picture of the Sierpinski Triangle! Using different starting shapes and fractions (i.e. "half way"), you can create a lot of cool patterns.
Tonight I made a simulation in javascript to see what would happen if you did this in 3 dimensions with a tetrahedron. I theorized it would give you the Sierpinski Tetrahedron (Sierpinski's Gasket). Turns out I was right!