Under the Night Sky

Sudoku - a cozy offline logic puzzle

Every number has a place. Light up the night. Place the nine stars so every row, column, and box has a complete constellation.

Download on the App Store More sudoku and logic

Inside Just One More · iPhone & iPad · iOS 18.2+ · Free with in-app purchases

Sudoku in Just One More, under the Night Sky

📵Plays fully offline
🪶Four difficulty levels
🎲6 ways to play
☀️In the daily puzzle rotation

How to play Sudoku

Light up the night. Place the nine stars so every row, column, and box has a complete constellation.

Fill the Sky

A 9×9 grid of nine 3×3 boxes. Place a star (1–9) in every empty cell to finish the constellation.
Once Per Row, Column, Box

Every row, every column, and every 3×3 box must contain each digit 1 through 9 exactly once. No repeats.
Pencil-Mark Candidates

Tap a cell and use the keypad below to enter a star. Use the notes mode to jot small candidate digits while you work things out.
Logic Only

Every puzzle has a single solution found by pure logic, with no guessing required. Look for cells with only one possible digit and work outward.

Four difficulty levels

Every level keeps its own streak, best and high score, so climbing costs you nothing.

Easy: 42 stars already lit. A friendly first sky.
Medium: 34 starting clues. The classic constellation.
Hard: 28 clues. Logic and patience. No guessing.
Very Hard: Just 22 clues. A nearly-empty night sky.

6 ways to play Sudoku

Classic Sudoku plus 5 more, each with genuinely different rules rather than a fresh coat of paint. Every one keeps its own difficulty ladder and its own best score.

X-Sudoku

X marks the spot.

Diagonals fill 1–9 too

How X-Sudoku differs

Fill the Sky Same 9×9 grid, same nine 3×3 boxes. Every row, column, and box still contains each digit 1–9 exactly once.
Diagonals Also Fill 1–9 Both main diagonals (top-left to bottom-right and top-right to bottom-left) must also contain every digit exactly once. Two new constraints to track.
Earlier Deductions Cells on a diagonal start with extra constraints. Fewer candidates, faster eliminations. Scan the diagonals first, then the row/column/box.
Logic Only Every X-Sudoku puzzle has a single solution found by logic. The diagonal rule is your friend. It often pins a digit when standard scanning won't.

Hyper Sudoku

Some truths overlap.

Four extra hidden 3×3 boxes

How Hyper Sudoku differs

Fill the Sky Same 9×9 grid, same nine 3×3 boxes. Every row, column, and box contains each digit 1–9 exactly once.
Four Extra Regions Four extra 3×3 boxes float in the interior of the grid. Each one must also contain every digit 1–9 exactly once.
Watch the Overlaps Hyper regions overlap with the standard boxes. Placing a digit in a shared cell rules it out twice. Hunt the overlap cells first.
Logic Only Every Hyper-Sudoku puzzle is solvable by deduction alone. The hidden regions often crack a wedge the normal scan misses.

Killer Sudoku

Every total has its cost.

Cages with target sums

How Killer Sudoku differs

Fill the Sky Same 9×9 grid, same row/column/box rule. Every region contains 1–9 once. The puzzle starts with very few clues; the cages do the rest of the work.
Cages with Sums Dashed outlines group cells into cages. The small number in a cage's corner is the sum the digits inside must total.
No Repeats in a Cage Digits inside a single cage can't repeat. Combined with the sum, a cage's possible digits often collapses to just one or two combinations.
Combinations First Lean on small cages (size 2 or 3). Their sums map to short, well-known digit sets. Solve those first to seed the rest of the board.

Thermo Sudoku

You can only go up from here.

Climb the thermometer 1→9

How Thermo Sudoku differs

Fill the Sky Same 9×9 grid, same row/column/box rule. Every region contains 1–9 once.
Thermometers Climb Each thermometer is a path from a round bulb to a tip. The digits along the path must strictly increase from bulb to tip.
Pin the Ends A 5-cell thermometer forces its bulb ≤ 5 and its tip ≥ 5. Long thermos collapse candidates fast from both ends.
Logic Only Every Thermo-Sudoku puzzle is solvable by deduction. Mark candidates along a thermo first. The strict-increase rule does most of the elimination for you.

Arrow Sudoku

Every arrow finds its mark.

Shafts sum to the mark

How Arrow Sudoku differs

Fill the Sky Same 9×9 grid, same row/column/box rule. Every region contains 1–9 once.
Shafts Sum to the Mark Each arrow has a hollow circle (the mark) and a shaft of cells running away from it. The digits along the shaft must add up to the digit written in the circle.
No Repeats on a Shaft Digits along a single arrow's shaft can't repeat. A two-cell shaft summing to 7 is 1+6, 2+5, or 3+4, never 3+4 the same way twice.
Logic Only Every Arrow-Sudoku puzzle is solvable by deduction. Short shafts and small circles collapse fast. A circle of 4 with a two-cell shaft is forced to 1+3.

Sudoku plays completely offline

Every round of Sudoku is generated, played and saved on your own device. There is no account, no sync and no server to reach, so it works the same on a plane, in a tunnel or with the phone in airplane mode. Sudoku also takes its turn as the daily puzzle, one shared board a day that is identical on every device.

Questions about Sudoku

Does Sudoku work without internet?

Yes. Sudoku generates every round on your device and saves your progress there too, so it plays exactly the same on a plane, on the underground or with the phone in airplane mode. Nothing in Just One More needs a connection.

How hard does Sudoku get?

There are four levels. Easy is "42 stars already lit. A friendly first sky." Very Hard is "Just 22 clues. A nearly-empty night sky." Your streak, best and high score are tracked separately for each level, so moving up never costs you what you earned lower down.

Are there other ways to play Sudoku?

Yes. 5 more games share the Sudoku board, changing the rules rather than the look: X-Sudoku (Diagonals fill 1–9 too), Hyper Sudoku (Four extra hidden 3×3 boxes), Killer Sudoku (Cages with target sums), Thermo Sudoku (Climb the thermometer 1→9), Arrow Sudoku (Shafts sum to the mark). Each keeps its own difficulty ladder and its own best score.

Is Sudoku in the daily puzzle?

Yes. Sudoku is one of the 13 games in the daily puzzle rotation. When its turn comes round, everybody gets the same board on the same day, and finishing it adds to your daily streak without touching your free-play progress.

Is Sudoku free?

Yes. Sudoku and the other 68 games in Just One More are free to play and ad supported, with an optional one-time Remove Ads purchase. No game, level or difficulty is locked behind a payment.