PADLOCK

PADLOCK is a code-breaking puzzle in the tradition of Mastermind and Bulls and Cows, played with digits. Each day there are hidden combinations, the same for every player, and you enter guesses of four digits (or five in the bigger locks) until the lock opens. It was invented by Elizabeth Wilson, who wanted a Wordle-like daily that her children could play without knowing hard words, and coded by her husband Mark under the name Fun Thinking Limited.

There are two ways to play, each in a four-digit and a five-digit size. In basic PADLOCK the digits of your guess turn green when they are in the right place, yellow when they are in the code but elsewhere, and grey when they are not in it, and you have five goes. In advanced PADLOCK, the lock on the front page, the digits stay plain: a small block of squares beside each guess shows how many digits are right and how many are misplaced, without saying which, and you get ten goes. A digit can appear more than once in a code.

Each lock is numbered, and a countdown shows when the next arrives: at your local midnight by default, or at midnight UTC if you change the setting. Your statistics, streak and win distribution are kept in the browser, and a share button copies your result as coloured squares.

No vocabulary or arithmetic is needed, which makes it suit children, classrooms and anyone who likes pure deduction. The same makers run Alphalock, a word version, and DUOLOCK, which has two boards at once.