THE SETUP
Hidato was invented by mathematician Gyora Benedek and published under that name internationally. GridJoy calls the same puzzle Starlink. Same rules:
- The grid contains N cells. You must place every integer from 1 to N, one per cell.
- Consecutive integers must occupy adjacent cells. Adjacency includes diagonals — each cell has up to 8 neighbours on a square grid.
- Some integers are already placed as given clues. The path must connect them all in order.
The diagonal adjacency is what distinguishes Hidato from Number Mazes, where only the four orthogonal directions count. Eight neighbours per cell means the path has far more routing options — which makes large gaps harder to eliminate, but corner constraints sharper.
THINK IN GAPS, NOT CELLS
The key mental shift in Hidato is to stop looking at individual cells and start looking at the gaps between given numbers. A gap of size G between two given numbers means exactly G cells must be threaded into a connected path between them — the path can bend and wind, but it must stay within cells that are reachable from both endpoints.
A gap of 1 is trivially forced: the two givens must be adjacent, and there is exactly one cell between them (or they share an edge). A gap of 2 or 3 offers few routing options near walls or corners.
Always sort gaps by size. Work smallest gaps first — they have the fewest routing options and therefore produce the most useful forced placements. Large gaps (10 or more cells) should be ignored until smaller gaps have been filled, because each filled gap eliminates cells that might otherwise seem available to the large one.
CORNER AND EDGE CONSTRAINTS
A cell in the interior of the grid has 8 neighbours. A cell on the edge has 5. A corner cell has only 3. The path must enter and leave every non-endpoint cell — meaning any non-endpoint cell must have at least 2 neighbours available to the path.
A corner cell that isn't the start or end of the sequence can only be reached and exited through 3 possible neighbours. If the cell at a corner must be somewhere in the middle of the chain, two of those three neighbours must be consecutive numbers. That constraint often pins the exact number in the corner.
Practical rule: any given number that sits one or two cells away from a corner forces very few routing options — check it early.
DEAD-END DETECTION
As you fill cells, some empty cells become surrounded by already-filled cells on all sides but one or two. If a cell has only one empty neighbour remaining, that neighbour must contain a number consecutive to it — otherwise the chain cannot enter or exit.
This is the Hidato equivalent of naked singles in Sudoku: an empty cell that is reachable from only one direction forces the number that must be placed next to it. Scan for near-dead-ends after every placement — they cascade quickly.
HOW IT COMPARES TO NUMBER MAZES
Both Hidato and Number Mazes ask you to fill a grid with a consecutive path. The difference is adjacency: Number Mazes uses only four orthogonal directions (up, down, left, right), while Hidato includes all eight (adding the four diagonals).
Four neighbours vs eight changes the puzzle substantially. Number Mazes paths are more constrained — the grid fills up faster and dead- end detection fires sooner. Hidato paths have more routing freedom, which makes the gap-analysis stage genuinely harder on large grids. The corner-constraint technique compensates: corners are cheap entry points in Hidato in a way they aren't in Number Mazes.
THE SOLVE ORDER
- List all gaps between given numbers. Sort smallest first.
- Fill the smallest gaps — these are often forced or near-forced.
- Check corner and edge cells for routing constraints and fill any that are pinned.
- After each placement, check for near-dead-end cells (one free neighbour) and resolve them.
- Move to the next-smallest unfilled gap and repeat.
Most beginner and intermediate Hidato grids unravel entirely from this order. Harder grids on larger boards may require occasionally trying a routing direction and checking whether it traps a later gap — but even then, the gap-analysis framework tells you exactly where the tension is.