Hidoku — Free Number Path Puzzle for Kids 6–10
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Hidoku is a number path puzzle: a square grid, a handful of numbers already printed on it, and one job — lay the whole chain from 1 to the very last number so that every step lands on a square that touches the previous one by a side.
Every level has exactly one answer, and it is provable
These grids are not scattered by hand. Each one starts as a full path built by machine, then clues are taken away one at a time, and after every removal a solver has to prove the puzzle still has a single solution. If it cannot prove it, the clue goes back. So there is never a moment where a child has to guess between two equally good moves — everything on the board can be reasoned out.
Four chapters, 80 levels, grids that grow
Levels 1–16 are 6×6 — thirty-six squares, and plenty of numbers given. Levels 17–36 move to 7×7, levels 37–58 to 8×8, and the last chapter, 59–80, is a full 9×9 grid: eighty-one squares with only a couple of dozen clues on them. Inside each chapter the clues thin out level by level, so the jump is never a cliff.
Steps go sideways, never diagonally
This is the rule that makes the puzzle work. The next number must sit directly above, below, left or right of the one before it — corners do not count. It sounds like a small restriction and it changes everything: a corner square with only two side-neighbours can often be pinned down long before the rest of the board.
The board answers back
Tap a number and it becomes the pen; tap it again and the pen counts backwards instead, which is how you work down from a large clue. Then tap the neighbouring empty square and the next number lands there. If a square is provably impossible — too far from the next clue to be reached in the moves left — the board simply will not take it. There is no red cross and no lost life; the move just does not happen, so the child looks again.
How to play
Tap or click a number on the grid to pick up the pen. A second tap on the same number flips the direction, so you can count backwards from a clue as easily as forwards. Now tap an empty square that touches it by a side — the next number appears. Keep going until the chain runs into the next clue, then start somewhere else. Undo takes back the last number, restart clears the level to its printed clues, and progress is kept on the device, so the next session opens on the level you stopped at.
What your child learns
Counting forward and backward in a place where it actually matters: to close a gap between the clue 23 and the clue 31 a child has to know how many steps are in between, and then find seven squares that fit. Along the way the puzzle drills the two habits every logic puzzle rests on — checking whether a move can still be undone later, and noticing when a square has only one way in and one way out. Because every level is proved to have a single answer, a child who reasons is always right and a child who guesses gets stuck; that is the lesson the grid teaches on its own.
The science behind the games
Every Dad4Kids game is built on one simple truth: children want to play, not study — so we turn learning into a game worth replaying. The method draws on peer-reviewed research in game-based learning, motivation, and how memory works.
- Prins et al. (2013). “Braingame Brian”: toward an executive function training program with game elements. Games for Health Journal.
- Tokac et al. (2019). Effects of game-based learning on students' mathematics achievement: A meta-analysis. Journal of Computer Assisted Learning.
- Alotaibi (2024). Game-based learning in early childhood education: a systematic review and meta-analysis. Frontiers in Psychology.
- Lampropoulos & Sidiropoulos (2024). Impact of gamification on students' learning outcomes and academic performance: a meta-analysis. Education Sciences.
- Taylor & Boyer (2019). Play-based learning: evidence-based research to improve children's learning experiences. Early Childhood Education Journal.
- Gottfried (1990). Academic intrinsic motivation in young elementary school children. Journal of Educational Psychology.
FAQ
How do you play hidoku?
You are given a grid with some numbers already filled in, and you complete the chain of consecutive numbers from 1 upward. Each number must be placed in a square touching the previous one by a side — up, down, left or right, never a corner. When the last number lands, the whole grid is full and the path is complete.
Are Hidato and Sudoku the same?
No. Sudoku is about which digits may share a row, a column or a box — the same nine digits over and over. A number path puzzle is about a single unbroken chain: every number appears once, in order, and the challenge is the shape of the route rather than the digits. The two puzzles are cousins in style but the reasoning is different. This game is the sideways-steps kind — no diagonal moves, which is what separates it from the version many people know by the brand name Numbrix.
What is a number puzzle called where you connect numbers in order?
Most commonly a number path or number chain puzzle; the sideways-only variety is also sold as hidoku. Whatever the name, the rule is the same: fill the grid so that 1, 2, 3 … run through neighbouring squares without a break.
How do you start a number grid puzzle?
Look for two clues that are close together in value — say 14 and 17. Only two squares are unknown between them, so there are very few routes, and often only one that does not trap the path later. Corners and edges are the next place to look: a corner square has just two neighbours, so the chain has almost no choice there.
What age is this puzzle for?
About 6 to 10. A six-year-old works comfortably on the 6×6 chapter, where the clues are dense and the counting stays small. The 9×9 chapter at the end is real work for a nine or ten-year-old — eighty-one squares and only a couple of dozen numbers given.
Does it work on a tablet?
Yes. Tapping a square is the natural gesture for this puzzle, and the grid scales to the screen. On a computer a mouse click does exactly the same job.
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By Evgeny Arsentiev, PhD · Last updated: September 2026