hidato · 6 min read
How to Play Hidato
Number every cell so consecutive values form an unbroken chain.
Hidato is a number-snake puzzle. The grid hides a hidden chain of consecutive numbers from 1 to N (where N is the total cell count), and each number sits next to the one before it. A few cells are pre-filled — your job is to figure out where every other number goes so the chain winds through every cell exactly once.
It rewards spatial reasoning more than arithmetic. Once you internalize one technique — “sandwich” deductions — easy puzzles fall in a few minutes.
The Puzzle
Here is a 5×5 puzzle. The bold numbers on off-white are the givens — they are fixed. Notice that the cells holding 1 (green) and 25 (amber) are also given — that's standard for Hidato; the start and end of the chain are always known.
The Two Rules
Rule 1: Use every number from 1 to N exactly once
On a 5×5 grid there are 25 cells, so the chain runs 1 through 25. On a 6×6 it would be 1 through 36. Each number appears exactly once and every cell holds exactly one number.
Rule 2: Consecutive numbers must be adjacent — including diagonals
For any value V (where V < N), the cell holding V+1 must be one of the 8 cells touching the cell holding V. This includes diagonal neighbors — Hidato uses the “king's move” from chess.
The Sandwich Technique
When you see two givens that are consecutive but not equal — like 13 and 15 — the missing value (14) must be in a cell adjacent to both givens. Often only one empty cell satisfies that. That's the sandwich technique, and it's how you crack the puzzle.
Walkthrough
Step 1 — Sandwich 15 and 17 → place 16
The givens 15 (at row 1, column 3) and 17 (at row 1, column 5) are only two apart. The cell holding 16 must be adjacent to both. List the empty cells touching each:
- Empty cells adjacent to 15: row 1 col 4, row 2 col 4 (others taken).
- Empty cells adjacent to 17: row 1 col 4, row 2 col 5 (others taken).
- Intersection: row 1 column 4. That's the only candidate.
Place 16:
Step 2 — Sandwich 13 and 15 → place 14
Same trick. 13 is at (1, 2), 15 is at (1, 3). The cell holding 14 must touch both. Cells adjacent to both that are still empty: row 2 col 2.
Step 3 — Sandwich 11 and 13 → place 12
11 is at (2, 1), 13 is at (1, 2). Cells adjacent to both: row 1 col 1 and row 2 col 2. But row 2 col 2 just got 14 in the previous step — eliminated. So 12 must go at row 1 column 1.
Step 4 — Five more sandwiches
The same technique resolves the rest of the “easy” values in quick succession. For each pair of consecutive givens, find the single empty cell adjacent to both:
| Sandwich | Missing | Only empty cell touching both |
|---|---|---|
| 21 + 23 | 22 | row 3 column 4 |
| 19 + 21 | 20 | row 4 column 4 |
| 17 + 19 | 18 | row 2 column 5 |
| 9 + 11 | 10 | row 3 column 1 |
| 7 + 9 | 8 | row 4 column 1 |
Step 5 — Path-tracing for the bottom row
The whole bottom row is empty. We need to thread the values 2, 3, 4, 5, 6 through it: starting next to 1 (at row 4 col 5) and ending next to 7 (at row 4 col 2).
Try following the chain from 1 outward:
- 2 must touch 1. The empty neighbors of 1 are row 5 cols 4 and 5. Try 2 at row 5 col 5.
- 3 must touch 2. Empty neighbors of (5, 5): only row 5 col 4. Place 3 there.
- 4 must touch 3. Empty neighbors: only row 5 col 3.
- 5 must touch 4. Only row 5 col 2.
- 6 must touch 5 AND must touch 7 at (4, 2). The remaining cell row 5 col 1 satisfies both (diagonally adjacent to 7). Place it.
Try the other branch (2 at row 5 col 4 instead) and you'll hit a dead end within two moves — so the path above is the unique solution.
Tips for Beginners
- Hunt for sandwiches first. Any pair of givens with values 2 apart (X and X+2) gives you a placement target for X+1. They are the easiest deductions in the puzzle.
- Then try gaps of 3. If you see X and X+3, then both X+1 and X+2 sit in the chain between them. They form a 2-cell path between the anchors — often easy to deduce too.
- Walk outward from 1 and N. The cells holding 1 and N are your best anchors — there's no “before 1” or “after N”, so 2 must touch 1 and N−1 must touch N. Often you can chain a few placements just from these.
- Branch and check. When two cells are valid options, try one and chase the consequences. Hidato puzzles are usually small enough that a wrong branch dead-ends in 2-3 moves.
- Don't forget diagonals. Beginners often miss the 4 diagonal neighbors of a cell. The “king's move” gives you 8 options, not 4.
Ready to try one yourself? Hit the button below to play your first Hidato.