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Lizely

Hidato

Solve a compact, uniquely determined Hidato number path with immutable clues, eight-direction adjacency, complete keyboard play, and independently verified logic.

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How to use

  1. 1.Select an unshaded cell and enter an exact value from 1 through 16 with the number pad or keyboard; the six shaded clue values cannot be changed.
  2. 2.Use every value exactly once, arranging the path so each consecutive pair touches horizontally, vertically, or diagonally.
  3. 3.Fill all 16 cells before checking; an incomplete check costs nothing, the first wrong full board can be repaired, and the unique solution earns exactly 1,000 points.

About Hidato

Hidato is a number-path logic puzzle. Fill every active cell with one integer from the puzzle's minimum through its maximum, using each value exactly once. Every consecutive pair must occupy touching cells: horizontal, vertical, and diagonal contact all count. A completed path therefore travels from 1 to 2, then 3, and continues without a gap until 16 on this board. Given numbers anchor parts of that route and cannot be moved or replaced.

This Lizely edition uses a fixed 4 by 4 board designed for a quick but genuine deduction session. Its six clues are 1, 2, 6, 10, 12, and 16. The layout, completed path, interaction policy, scoring, and mistake rules are original product fixtures. It is not copied from the official Hidato site, Smithsonian, a book, a newspaper, or another puzzle publisher. Those sources are cited only to establish the standard consecutive-number and eight-neighbor rules. The small board keeps the complete state visible on a phone while still requiring diagonal as well as orthogonal reasoning.

Select any non-clue cell and choose an exact value from the on-screen 1 through 16 pad. Selecting a different cell moves the visible cursor without changing the board. Clear selected removes an entered number, but it never changes a shaded clue. The board intentionally allows a temporary duplicate while you reason; duplicates are diagnosed when a complete board is checked instead of silently moving or deleting another entry. This keeps every edit explicit and makes correction predictable.

Keyboard control covers the entire game. Arrow keys move the cursor one cell at a time. Type a one- or two-digit value from 1 through 16 to place it. The short entry buffer lets 1 followed by 4 become 14; moving the cursor or using a number button starts a fresh entry. Delete or Backspace clears the selected editable cell, and Enter checks the board. The shared double-Escape gesture opens the spreadsheet-style boss screen, and another double Escape returns to the puzzle. Restart restores all six givens, clears every player entry, resets the cursor, score, mistakes, and feedback, and begins a clean run.

Checking distinguishes unfinished reasoning from a genuinely wrong completed attempt. If even one editable cell is empty, the game reports that the path is incomplete and records no mistake. Once all 16 cells contain values, the validator requires the exact integer range with no repeats, confirms every immutable clue, locates every value, and checks that each pair from 1-2 through 15-16 is separated by at most one row and one column. A first incorrect complete board records one mistake but remains editable. A second incorrect complete check deadlocks the run until Restart. A valid complete board awards exactly 1,000 points.

Completion and deadlock are terminal states. After either one, cell selection, number buttons, clearing, cursor movement, digit entry, and additional checking cannot change the result. This freeze is covered by the logic test rather than being only a visual disabled state. The first-error repair path is also exercised: the test submits a full invalid board, replaces its editable entries with the independently established solution, checks again, and confirms exact scoring. Incomplete checks, fixed-clue protection, cursor boundaries, multi-digit entry, and deterministic Restart are covered separately.

The fixture's uniqueness is not assumed from the displayed answer and is not proved by calling the runtime validator repeatedly. A separate test-only backtracking oracle constructs the 4 by 4 king-move graph independently. It reserves clue cells, walks values in numeric order, rejects occupied cells and non-neighbor transitions, and stops only after completing a path through all 16 cells. With all six clues it finds exactly one solution. The test then performs six more searches, removing one different clue each time. Every reduced clue set admits at least two solutions, proving that all six published clues are individually necessary rather than decorative hints.

Golden rule checks cover representative horizontal, vertical, and diagonal consecutive links. Negative fixtures cover a separated consecutive pair, a repeated value that necessarily omits another required value, and a fully populated invalid route. Structural invariants assert a 4 by 4 grid, 16 active cells, the exact 1 through 16 range, six distinct clue cells, six distinct clue values, eight allowed neighboring directions, one independently found solution, and six necessary clues. The disclosed solution places 2, 4, 5, 6 across the first row; 3, 1, 8, 7 across the second; 15, 9, 10, 11 across the third; and 16, 14, 13, 12 across the fourth.

Everything runs inside the browser as a small React client game. No board state is uploaded, no account is required, no random daily puzzle is fetched, and no new package dependency is used. Each board cell exposes its row, column, value, clue status, selection state, and stable test identifier. The four-column board and controls use large native buttons, wrapping status text, and a constrained width intended to avoid horizontal scrolling at 390 pixels. Color is supplemented by text and accessible labels, so clue and entry status do not depend on appearance alone.

This game is recreational. It is not an intelligence test, medical or psychological assessment, educational placement tool, or employment screen. Because the fixture is fixed, replay becomes easier through memory, so elapsed time does not affect the score. For a fresh solve, inspect the forced links around 1 and 2, then work backward from 16 toward 12. Compare how many moves are available between distant clues before committing a number. Use temporary duplicates if they help explore a branch, clear them explicitly, and check only after every cell contains a deliberate value.

Methodology & sources

Keep six authored clue cells immutable and let each other cell hold empty or one integer from 1 through 16. On a complete check, require 16 in-range integers with no duplicates, confirm every clue, map each value to its cell, and require each n and n plus 1 pair to differ by no more than one row and one column. Award exactly 1,000 only when every predicate passes, record no error for an incomplete board, allow repair after the first fully populated invalid board, deadlock after the second, and freeze both terminal states. Independently backtrack over the 4 by 4 king-move graph to prove one solution and rerun after removing each clue to prove all six necessary.

Frequently asked questions

What are the standard Hidato rules?
Fill every active cell with the consecutive number range exactly once. Each number must touch the next one horizontally, vertically, or diagonally, while the given clue cells stay fixed.
Does this fixed Hidato board have only one solution?
Yes. An independent backtracking oracle finds exactly one path with all six clues. Removing any single clue produces at least two paths, so every clue is necessary for uniqueness.
Can I play Hidato on a phone or entirely by keyboard?
Yes. The board and number pad support touch. Keyboard players can use Arrow keys, type values 1 through 16, press Delete to clear, and press Enter to check.
Is this an official puzzle or a cognitive assessment?
No. The board is an original Lizely recreational fixture. Hidato and Smithsonian are cited for rules only, and the score is not a measure of intelligence, health, education, or work ability.

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