On April 8, 2020, John Horton Conway developed symptoms of COVID-19. On April 11, 2020, he succumbed to the disease.1234 Like so very, very many, I mourn Conway’s passing, and yet I also celebrate his life. I celebrate his accomplishments, I celebrate his curiosity, and I celebrate his skill at making important topics in mathematics engaging and interesting. One of the finest examples of that skill is the programming language FRACTRAN, the subject of this essay. Prelude John Horton Conway in 199...