I built Numbergram which is a daily math puzzle inspired by the game Sydney train commuters play using carriage numbers to pass the time. The game is entirely client-side, with daily numbers and solutions pre-computed during a periodic build process. I actually developed this before AI became the primary way to develop these things, so got to learn a lot and get my hands dirty - particularly with implementing localisation (with my rusty Greek) and understanding methods to check equation equivalency.