Logic, chance & play

Puzzles and Games

A puzzle is a rule you can hold in your head and a grid that tests it. These are the classic games, played the way you know them, and then taken apart — the rules changed, the board resized, a coach that says why a move works — so you can see what makes each one tick. Every puzzle is made in your browser from a number, so a link can hand someone the exact same one.

Sudoku

The classic, made fresh each time with exactly one solution, and six ways to change the rules: diagonals, knight’s moves, jigsaw regions, odd and even cells, cages that add up and thermometers. Grids from 4 × 4 to 16 × 16, pencil marks, a daily puzzle, and a coach that names the technique behind every hint.

one solution, checked · seven rule sets · nine named techniques

Open

More is coming here. Sudoku is the first. Other games will follow in the same way: the traditional version first, then new ways to play it.

Made on your device. Puzzles are generated in the page from a seed and checked for a single answer there; nothing is downloaded or sent. An unfinished game and your best times are kept in this browser only.

Rules of thumb are approximations, offered to get you to the right order of magnitude fast. Check anything load-bearing against its source or the exact tool. Privacy · Terms