the recently discovered aperiodic monotile:
by Smith, Myers, Kaplan, and Goodman-Strauss, 2023
The monotile is a surprisingly simple shape that, when tiled compactly across a plane of any size, creates a never-repeating pattern. It was hard to discover but it's easy to use, and creates endlessly variable, endlessly complex output from a very simple input.
Systems design 2: What we hope we know by apenwarr