Fill the grid. Trust the logic.
Sudoku is a number-placement logic puzzle published in its modern form by the Japanese magazine Nikoli in 1984 and popularised globally by British and American newspapers in the mid-2000s. The objective is to fill a 9×9 grid so that every row, every column, and every 3×3 box contains each digit from 1 to 9 exactly once. No arithmetic whatsoever is required — only pure logic and systematic deduction. GameNight.pro features four difficulty levels (Easy, Medium, Hard, and Expert), pencil-mark candidate tracking, an optional auto-validate mode, undo, a hint function, and a timer. Every puzzle is uniquely solvable without guessing at lower difficulties, making each solve a satisfying exercise in deductive reasoning. No download or account required.
Click an empty cell to select it, then click a digit button or press a keyboard number to enter your answer. Switch to pencil mode to enter small candidate digits inside a cell for tracking possibilities on harder puzzles. The selected cell automatically highlights its entire row, column, and 3×3 box to help spot conflicts at a glance. Use Undo to reverse any move. Enable Auto-check to colour incorrect entries red in real time. Click Hint to reveal one confirmed correct digit. Your elapsed time is displayed at the top throughout the game. Press New Game to generate a fresh uniquely-solvable puzzle at the same or a different difficulty level.
Five solving techniques in order of complexity — master them to conquer every difficulty level:
Explore the full Sudoku Strategy Guide: Techniques for Every Difficulty for advanced methods including X-wings, swordfish, and forcing chains.