Sudoku (Puzzle Round)

Puzzle Round's Sudoku comes in three sizes, each a separate daily game with its own page and leaderboard. Mini Sudoku is a 4x4 grid using 1 to 4 with 2x2 boxes, a warm-up of a minute or so. Medium Sudoku is a 6x6 grid using 1 to 6 with 2x3 boxes. Classic Sudoku is the familiar 9x9 grid using 1 to 9 with 3x3 boxes.

The rules are the same in all three: fill every empty cell so each number appears once per row, once per column and once in each outlined box. Fixed clues are shown in teal, your selected number is highlighted in violet, and a number repeated in a line or box turns red. Select a cell and use the number buttons or the keyboard; choosing the same number again clears it. Each generated grid has exactly one solution.

The three sizes make a ladder: the Mini for a quick start, the Medium for a short session, the Classic for a full one. Puzzle Round also has an article on the history of Sudoku and Number Place.

Puzzle Round is a free website of short daily puzzles by thatsoftwaredude, an independent developer. Every player gets the same puzzles each day, a countdown on the site runs to the next midnight UTC, and each game keeps its own daily leaderboard ranked by solve time. You can play without signing up; a free account saves your result to the leaderboard and keeps your streak, and private Circles let a family or a group of friends compare results. Clearing the whole lineup in a day counts as a Perfect Day.