A deck of playing cards fanned out on a dark background

This holiday, I created calmjo, a version of Jo you can play on your phone. Play against the computer or your friends in real time. It was just released on the Apple app store.

Jo is the version of contract rummy most commonly played in Australia. It’s the game I played with my family growing up, and taught my children to play this holiday.

The game is free and doesn’t track you, except for the name you pick for the Hall of Fame and Hall of Shame. There are no ads. Let me know if you like it.

PS. For Jo masters, after running tens of thousands of simulated games, the AI recommends that you always go down as soon as possible even if you can go down immediately. The AI that plays the game is a small LLM model running on commodity hardware, so hopefully it won’t become self-aware.

PPS. for those interested in the tech stack, the backend infrastructure is simpler than my usual productivity SaaS services and apps. The backend is built in Go and uses a Postgres database to track games and high and low scores (Hall of Fame and Hall of Shame). Computer opponent moves are determined using a set of rules and a small LLM model hosted on the server. The server is a cheap commodity cloud server with very little RAM and no GPU. The app itself is written in pure Swift(UI).