Sudoku: frequently asked questions

MoonDoku is a modern, distraction-free Sudoku game, from gentle first puzzles to expert boards that make you hunt for every move. We focus on a clean interface, beautiful themes, and lo-fi chill vibes to help you relax while you play.

No — tonight's Nightly is free with no sign-up. A free account saves your streak, scores, and achievements everywhere you play, and you'll need one to buy the full game on the web (that's how your unlock follows you to any browser you sign into).

If you get stuck, a hint reveals the correct number in one empty cell — sometimes one cell is all it takes to get the logic flowing again. Hints are limited based on the difficulty level to keep things challenging.

Yes! Everyone can play tonight's Nightly free with no sign-up, and a free account saves your scores, streaks, and achievements across devices. The full game — unlimited puzzles at every difficulty — is a one-time purchase.

Four bands — easy, medium, hard and expert — graded by how much work a board takes to solve, not by how many digits are missing: a harder board needs more steps, trickier ones, and leaves fewer moves open at each point. Every board is solvable by logic alone — no guessing, at any level — and none needs advanced techniques like X-wings or chains.

One purchase unlocks every puzzle on moondoku.com: unlimited puzzles across every difficulty. All themes, music, and ambience are free for everyone.

$4.99, one-time — no subscription, nothing recurring. Pay once and every puzzle on moondoku.com is yours forever.

Email support@moondoku.com within 30 days and we'll refund your purchase, no questions asked — see the refund policy. Tonight's Nightly is free forever, so you can play as long as you like before buying.

Each edition is bought where it lives: the web unlock covers moondoku.com, and the iOS and Steam apps are complete games on their own. Your free account — streak, scores, and achievements — travels everywhere at no cost.