How to Play Logic Grid

Logic Grid is Sudoku-style deduction. You get a grid with some numbers already filled in. Fill the rest so that every row, every column and every box contains each number exactly once.

The three sizes

• 4×4 (easy) — numbers 1–4, boxes of 2×2. A gentle introduction.
• 6×6 (medium) — numbers 1–6, boxes of 2×3. The sweet spot for a coffee break.
• 9×9 (hard) — numbers 1–9, boxes of 3×3. The classic, and a real time investment.

How to play

1. Tap an empty cell and type a number.
2. If the number matches the hidden solution, it stays. If not, it counts as a mistake and the cell is marked.
3. Three mistakes end the game, and the solution is revealed so you can study it.
4. Hint fills one empty cell correctly. Use it sparingly — a hinted cell still counts as solved by you, but the satisfaction is smaller.
5. Fill every cell correctly to win. Your best time per size is saved in your browser.

The one rule that solves everything

Never guess when you can deduce. If a number already appears in a row, column or box, it cannot go anywhere else in that row, column or box. Cross off the impossible, and the possible reveals itself.

Related: Logic Grid tips & strategy.