Solo

Solo is an elegant implementation of the classic Sudoku puzzle. Played on a 9×9 grid divided into nine 3×3 boxes, the goal is simple yet deeply engaging: fill the grid so that every row, every column, and each 3×3 box contains all the digits from 1 to 9 exactly once.

The puzzle begins with a set of pre-filled clues, and your task is to deduce the missing numbers using logic alone—no guessing required. Solo supports multiple grid sizes (including 4×4, 6×6, 8×8, and custom variants) and offers adjustable difficulty levels, making it accessible to beginners and challenging for experts alike.

The interface of Solo is clean and intuitive: click a cell to select it, then type a number or use the on-screen keypad. Mistakes are highlighted in real time, and hints are available if you get stuck—perfect for a quick brain teaser or a deep logical workout.

Fill in a number in every square so that each number appears exactly once in every row, every column, and every block outlined by thick lines.

To place a number, click a square to select it, then type the number on your keyboard. To erase a number, select the square and press Backspace.

Right-click a square and then type a number to add or remove it as a pencil mark—indicating candidates you think might belong in that square.

Once you've mastered the basic game, try Jigsaw mode (with irregularly shaped blocks), X mode (where both main diagonals must also contain each number exactly once), Killer mode (where instead of given numbers, you're shown regions that must each sum to a specified total without repeating digits), or even combine all three for an extra challenge!

Tip: On mobile devices, you can perform a "right-click" by using a long press.