How to play

The sudoku rule

Fill the grid so that every row, every column and every 3×3 box holds each digit from 1 to 9 exactly once. Some digits are given at the start; you work out the rest by logic, never by guessing.

Every puzzle here has exactly one solution.

Difficulties

There are four difficulties. A puzzle's difficulty comes from the hardest solving technique it needs, not from how many digits are given. Each level may need the techniques below.

• Easy · 12 steps and 1 shell per solve

  Hidden single, Naked single

• Medium · 24 steps and 2 shells per solve

  Locked candidates (pointing), Locked candidates (claiming), Naked pair, Hidden pair

• Hard · 48 steps and 4 shells per solve

  X-Wing, Naked triple, Hidden triple, XY-Wing, Naked quad, Hidden quad

• Expert · 84 steps and 6 shells per solve

  Swordfish, XYZ-Wing, Simple coloring, Jellyfish

Learn each technique, with examples to try

Entering digits and notes

• Select a cell, then tap a digit on the number pad (or type 1–9).
• Turn on Notes (or press N) to write small candidate digits instead. A candidate already in the same row, column or box is refused, and placing a digit removes it from its neighbours’ notes.
• Erase clears a cell (or press Backspace or Delete).
• Undo takes back your last move (or press Ctrl+Z, ⌘Z on a Mac). Hints are never undone.
• With an account, Fast notes writes every candidate into every empty cell in one tap, for free. It only uses the digits on the board, so it never tells you which are wrong.
• When at most 10 cells are left and they're all easy (a single solves each), Auto-complete fills them for 2 shells. The clock stops at the tap, and the solve counts as usual.
• On a keyboard, the arrow keys move between cells.

Mistakes

Every digit you enter is checked. A wrong digit is marked and counts as a mistake, and mistake number 3 ends the game. The solution stays hidden, so a lost puzzle can be met again another time.

With an account, that mistake doesn't have to be the end: you're offered an extra life for 12 shells, the Daily included. The wrong digit is removed and you carry on, with one more mistake allowed. There's one extra life per puzzle, so the next mistake ends the game.

Hints

• Select an empty cell, or one with a wrong digit, and tap Hint: its right digit is written in. A hinted cell is marked, can't be changed, and never counts as a mistake.
• Hints come from your stock, which is bought with shells: 10 shells a hint. When you have none, tap the + on the Hint button to buy one and use it straight away.
• Up to 3 hints can be used in one game, however many you own.
• Hints need an account, because shells are earned by players with an account.

The timer and pausing

The clock runs while you play. Pause hides the board and stops the clock; it also stops when you switch tabs or visit another page, and your game waits for you.

The Daily sudoku

• Every day there is one Daily sudoku, the same for everyone. A new one starts at midnight UTC.
• Its difficulty follows the week: Monday and Tuesday Easy, Wednesday and Thursday Medium, Friday and Saturday Hard, Sunday Expert.
• If you lose it, you can try it again as many times as you like that day.
• Missed one? Every past Daily has its own page and is in the archive. Playing it later earns the usual steps and shells, but not the Daily bonus or your streak.
• Your first solve of the day earns 30 extra steps and 2 extra shells on top of its difficulty’s.

The Daily streak

• Solve the Daily every day to build a streak. A day without it ends the streak, but today doesn't count until it's over.
• Milestones earn shells: 7 days +10, 30 days +30, 100 days +75, 365 days +200.
• A streak freeze (20 shells, on the Shells page) covers a missed day by itself: the streak goes on, without growing that day.

Steps and the trail

Every solve earns steps, which show how far you have walked. Steps are never spent and never go down. As they add up you reach new places on the trail, through six regions, from the Trailhead to places very few will ever see:

1. Meadowlands

   1. Trailhead0 steps
   2. Meadow100 steps
   3. Beehive Hill400 steps
   4. Old Windmill800 steps
   5. Shepherd's Gate1,300 steps

2. Whispering Forest

   1. Forest Path1,900 steps
   2. Mossy Hollow2,700 steps
   3. Owl's Clearing3,600 steps
   4. Old Bridge4,800 steps
   5. Lantern Grove6,000 steps

3. River Valley

   1. River Crossing7,500 steps
   2. Stepping Stones9,500 steps
   3. Watermill12,000 steps
   4. Ninefold Lake14,500 steps
   5. Ferry Landing17,000 steps

4. Highlands

   1. Hill Village21,000 steps
   2. Terraced Vineyards25,000 steps
   3. Stone Circle30,000 steps
   4. Foothills35,000 steps
   5. Mountain Pass41,000 steps

5. Frozen Peaks

   1. Glacier50,000 steps
   2. Ice Caves60,000 steps
   3. High Camp70,000 steps
   4. The Ridge84,000 steps
   5. Summit100,000 steps

6. Sky Road

   1. Above the Clouds120,000 steps
   2. Aurora Fields200,000 steps
   3. Beyond the Peaks350,000 steps
   4. Moonlit Path600,000 steps
   5. Among the Stars1,000,000 steps

See your trail on the map

Shells

• Every solve also earns shells: Easy 1, Medium 2, Hard 4, Expert 6.
• Today's Daily adds 2, each new place on the trail adds 5, and each new region adds 20 on top.
• Shells are spent on help, like hints (10 shells each). Spending them never moves you back on the trail.
• Shells and steps can only be earned by playing. They can never be bought.

Leaderboards

The leaderboards rank players by the steps they earned today, this week and in all time. Today starts at midnight UTC, the week on Monday at midnight UTC. They show your username, icon, country flag (if you set one) and place on the trail.

See the leaderboards

Fair play

Every result on Sudoku Hike was really played here. That’s why the leaderboards, challenges and steps mean something:

• Every digit you enter is checked by our server as you enter it. The solution never reaches your browser, so it can’t be read from the page.
• A puzzle only counts as solved if every empty cell was filled during that game, so a finished grid can’t simply be sent in.
• A time can’t be longer than the game itself, and mistakes and hints are the server’s own count.
• A puzzle earns steps only once per account, and steps can never be bought, not with shells and not with money.

No site can stop someone from getting help elsewhere, from a book or a friend. What we can promise is that every result shown was played, move by move, on our site.

Guests and accounts

You can play without an account. With a free account, your games are saved, you get statistics, you earn steps and shells, and you appear on the leaderboards. Games played as a guest aren't added to an account later.

Create a free account