Gillespie explains in the video that he created a JavaScript Snake game 15 years ago. His goal was to shrink it down to the point where the game uses the individual subpixels of a monitor.

Fitting Snake Into A QR Code. 18 Comments . by: Danie Conradie. August 17, 2020. Title: ... To start, he first wrote Snake to run in a web browser using HTML, CSS, and JavaScript, ...