Chain Sudoku

A lighter, quicker cousin of Sudoku, played on a grid of linked circles. Chain Sudoku drops the 3×3 boxes and keeps just one rule, which makes it perfect for a short, satisfying solve.

The idea behind Chain Sudoku

Not every puzzle needs to fill a coffee break. Chain Sudoku is built for the spare minute: a small board, a single rule, and a finish line you can usually reach in a minute or two. The cells are drawn as a chain of connected circles rather than a hard square grid, which gives the puzzle a softer, more playful character. Underneath that friendly surface sits a classic piece of logic that mathematicians call a Latin square, the same structure Sudoku itself is built on.

How Chain Sudoku works

There is exactly one rule. Fill the grid so that every row and every column contains each number once, from 1 up to the size of the board. The smallest board runs 1 to 5, the largest 1 to 7. There are no 3×3 boxes and no arithmetic, which is what makes the puzzle so approachable. Because the grids are smaller than a full 9×9 Sudoku, the logic is tighter and the payoff comes faster.

Three sizes

• 5×5 (Easy) is the classic light chain, gentle and quick.
• 6×6 (Medium) gives a little more room to reason.
• 7×7 (Hard) is the biggest chain, with the fewest clues to start from.

Every puzzle is generated fresh with a single guaranteed solution, so you never need to guess.

The solving logic

Chain Sudoku is a pure exercise in cross-referencing. Start with the rows and columns that already hold the most numbers, because they have the fewest gaps to fill. When a number is missing from a row and only one open circle in that row can legally take it, place it. The key move is elimination: a number already sitting in a column cannot appear again anywhere in that column, so you can rule it out of every other circle there. Work the two directions against each other, row against column, and the board resolves steadily.

Because there are no boxes to consider, the reasoning is cleaner than in classic Sudoku, which is exactly why Chain Sudoku is such a good place for newcomers to feel how deduction works. Master it here and the jump to a full 9×9 board becomes far less daunting.

Why a smaller grid helps you learn

Chain Sudoku is more than a quick diversion; it is a genuinely good teacher. A full 9×9 Sudoku asks you to juggle three constraints at once, which can overwhelm a newcomer. By stripping the puzzle down to rows and columns on a small board, Chain Sudoku lets you feel each individual deduction clearly, with nothing else in the way. You learn to trust the logic, to scan systematically, and to spot the single open cell that must take a given number. Those instincts transfer straight to the larger grid, so time spent here is never wasted, whatever size you eventually prefer.

Built-in help

• Erase and undo to take back a move without losing your place.
• Hint to reveal a correct number when you are stuck.
• A running timer and a fresh board on demand at any of the three sizes.
• Automatic saving and the site's light or dark theme.

More puzzles

If you want the full grid back, play the number classic at Sudoku AZ, go visual with Color Sudoku, or add a little arithmetic with Killer Sudoku. Chain Sudoku is the one to reach for when you have five minutes and want a clean, complete puzzle in that time.