Writing

Notes from the studio.

Mostly about building software with one set of hands. Occasionally about typography, sleep, or why a sudoku grid should look like it was set in 1962.

11 POSTS

X-wing: one digit, two rows, two columns

The sixth technique, and the first one that spans the whole board rather than a single region.

Sudoku techniques, in the order worth learning them

The ladder is seven techniques long. The first three finish almost every Easy puzzle in our app; Hard needs more than all seven.

Naked pairs: two squares that own two numbers

The fourth technique. Two squares agree on the same two candidates, and everything around them gets smaller.

How to play Sudoku: the rules, and your first move

One of each digit per row, column and box. That is the entire rule set — the rest is what to do with it.

Hidden pairs: two numbers that own two squares

The fifth technique, and the one people skip. It looks like clutter until you know what you're looking at.

Pointing pairs: reading a box like a sentence

The third technique, and the first one that doesn't place a number. It clears the way for the ones that do.

Why our Sudoku app has no hint button

The feature we left out on purpose, and the line we used to decide what stays in.

Naked singles: the square that can only be one number

The first real Sudoku technique, explained without the jargon — and the one habit that gets you unstuck.

Hidden singles: the number with only one home

The second technique, and the one that gets you moving again when crossing off stops working.

Stuck on a Sudoku: five kinds of stuck and what each needs

Being stuck isn't one problem. Work out which one you've got and most of them take under a minute to clear.

On building a studio of one

What "AI factory" actually means when you're the only one in the building.