Jigger

The problem it solves

Most puzzle apps want an account, a subscription, an internet connection, and a phone. This one is a gift for a single non-technical user whose laptop is often offline. The measure of success is simple: is she still using it six months after it was installed?

So every design decision resolves in favour of her comfort over feature richness. If a feature adds a decision she has to make, it has to justify itself. The app should feel less like software and more like a box of puzzles on a shelf.

What it does

Launch it from a desktop icon, pick a photo, pick Easy, Medium or Hard, and do the puzzle. Pieces that belong together join with a soft gold glow and a click. Pieces that don't belong together won't join, however close you put them, so there is no such thing as a wrong join. Close the window whenever you like. Jigger remembers exactly where every piece was left and puts it back the next time, indefinitely.

It ships with a shelf of photographs, and new ones can be added from a button or by dropping them in a Puzzle Photos folder on the desktop. There are no scores, timers, streaks or accounts, and pieces never rotate. Nothing loads from the network at runtime, and a test fails the build if anything tries to.

It went onto her laptop on 27 September, by email through Posey, onto a machine that had no Python at all. Everything worked, and she has been doing several puzzles a day since.