What is Space Sudoku?
Space Sudoku (sometimes called Astronaut Sudoku, Galaxy Sudoku or Rocket Sudoku) is sudoku played with six space-themed icons instead of the digits 1–6. The rules are exactly the same — every row, column and box must contain each icon once — but you don’t need to read numbers to play. That makes it one of the friendliest, most exciting sudoku puzzles on the whole site.
The board is 6×6, split into six rectangular boxes of 2×3 cells. Some squares start with a space friend already drawn in (the "givens"), and your job is to fill in the rest using only logic. The six icons are a rocket, planet, star, moon, alien and comet — easy to tell apart even for very young space cadets, and each one wears a different colour to make spotting them even easier.
If your child has already played our 4×4 sudoku or 6×6 sudoku, the rules will feel familiar. The space version just swaps numbers for bright, kid-friendly cosmic icons, so even pre-readers can join the mission. It also pairs nicely with Shape Sudoku and Color Sudoku, which use shapes and colours in place of digits.
The 3 super-simple rules
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Every row uses every space friend
A row is a line going across the grid. Each of the six rows must contain all six space friends, with no repeats.
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Every column uses every space friend
A column is a line going down the grid. Each of the six columns must also contain all six space friends, with no repeats.
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Every 2×3 box uses every space friend
The board is split into six rectangular boxes — three across, two down. Each box must contain all six space friends once.
Meet the six space friends
- 🚀 **Rocket** — a red rocket ship blasting off, ready to explore the galaxy
- 🪐 **Planet** — a blue planet with a glowing ring around it
- ⭐ **Star** — a yellow five-pointed star shining brightly
- 🌙 **Moon** — a silver crescent moon, like the night sky
- 👽 **Alien** — a friendly green alien with big black eyes
- ☄️ **Comet** — a purple comet streaking past with a fiery tail
How to play step by step
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Tap an empty square
The square highlights and shows which row, column and box it belongs to.
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Pick a space friend from the pad
Six big icon buttons live next to the board. Tap the one you want and that space friend drops into the square.
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Check the row, column and box
Before you tap, scan the row, column and box for that square. Is that icon already there? If yes, try another.
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Use Notes when it gets tricky
Tap ✏️ Notes to add tiny icon marks — one for each space friend that *might* fit. Tap Auto Notes to fill them in everywhere automatically.
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Need help? Tap Hint
The Hint button reveals the correct icon for the selected square. Hints count in your stats but they’re always there to help.
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Tap Check before celebrating
If anything is wrong, Check tells you how many icons need fixing — without spoiling which ones.
Easy strategies for kids
- 🔍 Look for rows or columns with the most given icons — they’re easiest to finish
- ⭐ If a column already has a star, no other square in that column can be a star
- ✏️ Use Notes to mark "maybe rocket, maybe comet" before committing
- 🔁 After every placement, scan the row, column and box for new chain moves
- ✅ Tap Check whenever you feel stuck — it spots wrong icons fast
Older kids who already love numbers can switch back to a digit grid any time — try our 6×6 sudoku for the same 6×6 size with numbers instead of space friends, or classic 9×9 sudoku for the full 9×9 game.
Why Space Sudoku is great for young kids
- 🧒 No reading needed — perfect for ages 4–6
- 🚀 Big, bold space icons that pop on phones and tablets
- 🧩 Same brain workout as classic sudoku — pattern spotting and logic
- ⏱️ Most Easy puzzles finish in under 5 minutes
- 🪶 Calm, quiet activity — no timers ticking down, no pressure
- 👨👩👧 Great for playing together — parents name space friends, kids tap them
- 🌌 Sparks curiosity about space, planets and the night sky
Space Sudoku vs. number sudoku
- 🚀 Space Sudoku uses six space icons; number sudoku uses digits 1–6 or 1–9
- 👶 The space version works for younger kids who can’t yet read numbers
- 🧠 Same logic on both — pattern spotting, no arithmetic
- ⏱ A space grid is the same speed as a 6×6 number grid (3–10 minutes)
- 📱 Big space icons are easy to tap on a small phone screen
- 🎨 Bright colours make every square pop, even in low light
Ready for more?
Once Easy Space Sudoku feels comfortable, try Medium Space Sudoku. From there you can graduate to Hard Space Sudoku, and finally take on Expert Space Sudoku — our toughest space puzzle, with only a handful of starter icons on the board.
Want a totally different look? Try Shape Sudoku (the same 6×6 logic, played with six shapes), Color Sudoku (six colour swatches), Killer Sudoku (sudoku with cage sums) or Jigsaw Sudoku (sudoku with wiggly boxes).
Frequently asked questions
What age is Space Sudoku good for?
Most kids enjoy Space Sudoku from about age 4. Because there’s no reading or arithmetic, it works for pre-readers too — they just match space icons to the row, column and box rules.
Is Space Sudoku the same as Astronaut Sudoku or Galaxy Sudoku?
Yes — Space Sudoku, Astronaut Sudoku, Galaxy Sudoku and Rocket Sudoku are all names for sudoku played with space-themed pictures instead of digits. The rules are the same; only what fills the squares is different.
How is Space Sudoku different from a 6×6 number sudoku?
The board, rules and difficulty are the same. The only difference is what fills the squares: six space friends instead of the digits 1–6. Switching between them is like switching costumes — the game underneath is identical.
How is Space Sudoku different from Shape Sudoku?
They use the same 6×6 board and the same logic. Shape Sudoku uses six geometric shapes; Space Sudoku uses six space-themed icons (and each icon also has its own colour). Some kids prefer shapes, some prefer space — try both and see!
My child can’t read yet. Can they still play?
Yes — Space Sudoku is built for this. Each of the six icons is bright and recognisable, so the puzzle is solvable without ever reading a single word.
Can I play without making an account?
Yes! Every game on this site is free, with no signup, no email, and no ads in the way of the puzzle.
Does the puzzle save my progress?
Yes — your icons, notes and timer save automatically in your browser. Close the tab and come back later, and it will all still be there.
Try other sudoku games
Different look, same friendly logic. Pick a sibling puzzle to play next.