Daily Akari

Akari, also called Light Up, is a logic puzzle created by the Japanese publisher Nikoli. Daily Akari, made by Singfisher Games, gives it a friendly face: the black blocks smile when they have the right number of lights next to them, and lit squares change colour so you can see what is covered.

A light shines along its row and column until it hits a block or the edge of the grid. Two lights may never shine on each other, every white square must end up lit, and a block with a number needs exactly that many lights on its four sides. There is a right-click (or long press) to mark a square where no light can go, and the game shows which lights you placed most recently.

Each day's puzzle is numbered and is the same for every player; the grids come from puzzle authors around the world who have allowed the site to use them, and each is credited. Past puzzles are in an archive where their authors have agreed. Difficulty follows the week: easy on Mondays, harder towards the weekend, very hard on Saturdays and Sundays. A Pro Mode adds accuracy to your shared result, and the screens come in English, Japanese, Chinese, German, Portuguese and French. It suits anyone who likes sudoku-style logic but wants something different, and the grids range from gentle to tough.