In December 2012, a self-taught musician with no formal programming background sat up late reading a Wikipedia article about array data structures. A few years later, a copy of the game that sprang from that page was handed to Pope Francis at the Vatican. This deep dive tells the story of Toby Fox and Undertale, from RPG Maker 2000 tinkering and Earthbound ROM hacks to composing for Homestuck, a $5,000 Kickstarter that raised over $51,000, and a September 2015 release that became a cultural phenomenon.

We explore how Fox avoided feature creep by making his code and narrative inseparable, why he built a game where you could talk your way out of every fight, and how rewriting the Toriel encounter so players could spare her became the moment he discovered what his game was about. We also cover his music-first development process in FL Studio,  ...