Balatro is a roguelike survival game where you need to multiply "chips" and "mult" together to meet a requirement each round. You get three chances to draft enough resources to survive. I designed my own slide rule to help with the mental multiplication - most of the fun of the game comes from the mechanics being slightly obscured from the player.

Since I designed this slide rule myself, I was able to make a couple unconventional design choices that fit my needs. For instance, mine has three octaves so it can represent numbers within the ones, thousands, or millions' range, for example; no need to track arbitrary powers of ten. Since it's a rotary rule, it wraps around. Eg. 353×24 shows on the device as 8.47, so you can think of it as 8.47 thousand, for example.

Holding a physical object in my hands while playing helps more than I thought it would. Should I take a card that increases chips by 600 or increases mult by 1.3×? Do I need to take a card to clear the blind in the short term, or do I have enough resources to draft a slower card that will scale better over time? Even just looking at how densely packed the marks are on the "Chips" side vs the "Mult" side of the device gives a visceral physical sense of what my build needs to focus on.

Pictures and .STL: https://www.printables.com/model/1026662-jimbos-rotary-slide...

Github repository: https://github.com/gcr/balatro-slide-rule

The actual plotting code used Marimo notebooks, which host a python in your browser via WASM. Take a look here: https://marimo.app/l/4i15d7

I entered it in Printables’ educational tools competition but the other entries were cooler. Maybe HN might like it. :-)