Number Path Puzzle Online
Number Path asks you to place every integer from 1 through the final number so consecutive values touch horizontally or vertically. The rule is easy to state, but sparse clues create long gaps where distance, parity, occupied cells and nearby anchors must all agree before the unique route becomes clear.
How Number Path works
Every finished board contains the numbers 1 through N² exactly once. Number 2 must be orthogonally adjacent to 1, number 3 must touch 2, and the same rule continues until the final value. Diagonals do not connect. Some values are fixed clues and cannot be moved; every other number must be deduced.
The playable specialist uses Easy 6×6, Standard 8×8 and Challenge 10×10 boards. Easy sources start with 18 clues, Standard sources use 24 clues, and Challenge sources normally use 28 clues, with one frozen source requiring 31 clues to preserve a proven unique completion. The clue density is deliberately reduced as boards grow so the larger modes create longer reasoning gaps instead of only more cells.
The project does not download a remote Numbrix pack. Each source begins with a locally generated Hamiltonian path that visits every grid cell exactly once. A deterministic backbite transformation randomizes that path without breaking the one-visit property. Clues are then selected and an independent exact solver counts legal completions. A source enters the frozen bank only when that count is exactly one.
Start with anchor gaps
Look at two known numbers with missing values between them. If 20 and 27 are fixed, the path has seven orthogonal steps available to travel from the cell containing 20 to the cell containing 27. That numeric gap immediately limits where 21 through 26 can go.
The live monitor displays unresolved anchor gaps as distance divided by available steps. A gap marked 5/7 means the two anchors are five Manhattan steps apart with seven sequence steps available. There is room for a two-step detour. A gap marked 7/7 is tight: the route cannot waste any steps, so every move between those anchors must belong to a shortest orthogonal path.
If the Manhattan distance is greater than the number gap, the state is impossible. Parity matters too. A checkerboard grid changes color on every orthogonal move, so the distance parity must match the number-gap parity. The game flags a gap that violates either necessary condition instead of waiting until the end of the puzzle.
Use both directions
Many number-path interfaces encourage you to start at 1 and march upward. That works, but it can hide useful information at the high-number side of a gap. In this specialist you can select any filled clue or player number, choose Forward +1 or Backward -1, and extend the sequence from whichever side is more constrained.
Suppose 42 is fixed near a wall of already used cells while 35 is far away in open space. Working backward from 42 may immediately force 41 and 40 even when the forward route from 35 still has several possibilities. The active-number control makes that reasoning explicit rather than treating backward deductions as a special mode.
On pointer devices you can tap or drag through adjacent cells. When a drag reaches a fixed clue that is exactly the next required value, the clue is accepted as part of the chain and the active number advances through it. Desktop right-click erases a non-clue entry. Keyboard users can move with the arrow keys, select or place with Enter or Space, switch direction with F and B, erase with Delete, and use Ctrl/Command Z for Undo.
Read the candidate monitor carefully
For every missing number the local analyzer asks which unused cells are still compatible with the current known sequence. If the previous number is placed, a candidate must touch it. If the next number is placed, the candidate must touch that too. The cell must also remain within the Manhattan distance and parity budget of the nearest known lower and higher anchors.
A number with one remaining candidate is locally forced under those constraints. The monitor surfaces these low-candidate values instead of forcing you to scan the entire 10×10 board after every move. A value with several candidates is not presented as globally ambiguous or globally possible; the display is intentionally local because some candidates can later fail for constraints that are farther away.
This distinction matters for trust. The frozen source has one complete solution because the independent verifier counts full paths. The live candidate chips explain immediate consequences of the state you entered. They do not pretend to be a complete proof tree for every unfinished position.
Technique-aware Verified Hint
Verified Hint first looks for a missing number whose local candidate set has collapsed to one cell. When such a forced step exists, the hint uses that deduction and explains why the number is constrained. This is more useful than revealing an arbitrary square because it directs attention to the sequence rule that made progress possible.
If no immediate one-candidate step exists, the helper chooses a low-candidate missing number and reveals its location from the independently verified unique solution. Check and Verified Hint mark the run Assisted so clean solves stay meaningfully separate from runs completed with answer support.
Undo and Redo preserve experimentation. Browser-local autosave stores the current values, move history, active number, direction and elapsed time. A refresh returns to the same deterministic seeded Practice board instead of silently changing the puzzle.
Why the bank is independently verified
A generator can easily produce a completed Hamiltonian path and then remove clues. That alone does not prove the remaining puzzle has one solution. The V0.126 pipeline therefore uses a separate exact solver that reconstructs the sequence from the clue positions, rejects cells reserved by other clues, checks reachability to the next fixed number, and periodically verifies that the remaining unused region has not split into disconnected components.
The frozen bank has 60 sources: 20 Easy, 20 Standard and 20 Challenge. All 60 are independently valid and unique. Eight square symmetries are checked as transformed boards, giving 480 verified source-transform starts. Practice selection is deterministic from the URL seed. Daily Number Path uses a separate date-stable mapping and truthfully does not claim that all 365 dates must produce globally distinct starts.
Practice, Daily and repeat use
Practice is for unlimited seeded play at a chosen size. Daily Number Path gives one date-stable specialist puzzle with its own local completion history and streak. It remains outside the frozen Today’s 6 rotation, so adding this specialist does not alter the platform’s existing daily sequence contract.
The combination of deterministic replay, clean-versus-assisted records, autosave and an explanation-focused monitor is intended to make Number Path useful for more than a one-off solve. You can return to a difficult URL, compare a clean replay with an assisted first attempt, or use Daily mode as a separate short reasoning habit.
For a full puzzle, open the Number Path game. For the date-stable mode, open Daily Number Path. You can also add the specialist to My Mix or browse the broader logic game collection.