Zip game › Guide
Zip Game Strategy: Worked Path Deductions & Guide
To solve Zip puzzles without guessing, lock in cells with only two available neighbours—starting at unnumbered corners—never leave an unvisited cell with a single exit, and never let the path touch a border in a way that splits the empty cells into two regions.
Every Zip board on Solvedle is a Hamiltonian path puzzle: one continuous orthogonal line starts at 1, visits every square exactly once, passes the numbered clues in ascending order, and finishes on the highest number. Below are four verified checkpoints from released practice puzzles followed by a complete 6×6 walkthrough.
Four deductions that force moves in Zip
- Corner forced entry and exit (degree-2 rule): Every unvisited cell except the final number needs at least two free neighbours—one to enter and one to leave. A corner cell has only two neighbours on the entire grid, so unless that corner holds 1 or the final number, the path must use both of its incident edges.
- Dynamic dead-end avoidance: As the path grows, visited cells act like walls. Whenever an unvisited cell near the path head drops to just two remaining free neighbours (counting the current path head), the path must either step into it immediately or reserve both neighbours for it.
- Pocket sweep before adjacent clues: When numbers k and k+1 sit right next to each other near a border or corner, check whether stepping straight from k to k+1 strands the corner pocket behind them. If it does, the path must detour through the pocket before landing on k+1.
- No board splitting (connectivity): Running the path straight across the board to touch a wall can cut the remaining empty cells into two separate islands. Because the path cannot cross itself, one island can never be visited. Always keep unvisited cells in a single connected group.
Four real checkpoints from Solvedle practice boards
Each example below comes from a released puzzle in the Zip practice library, and the build script checks every claim against the board before it is published. Inspect the position, open the step to see the continuation, and click the puzzle link to play that exact board from move 1.
1. Corner Forced Entry and Exit (6×6 easy)
At R5C1, the adjacent corner R6C1 is not the final number (13) and has only two grid neighbours (R5C1 and R6C2). If the path bypasses R6C1, it becomes a dead end with at most one free neighbour. The path must step R5C1 → R6C1 → R6C2.
Head at R5C1; outlined cells are the ones this deduction uses.
Show the forced path continuation
2. Degree-Two Dead-End Avoidance (6×6 medium)
With the path head at R6C1, cell R5C1 has only two available neighbours left: R6C1 and R4C1. Leaving R6C1 in any other direction would reduce R5C1 to a single neighbour, stranding it permanently. The path is forced to go R6C1 → R5C1 → R4C1.
Head at R6C1; outlined cells are the ones this deduction uses.
Show the forced path continuation
3. Adjacent Clues That Cannot Connect Directly (7×7 medium)
Clues 17 (R6C6) and 18 (R5C6) are orthogonally adjacent, yet stepping directly from 17 to 18 leaves an empty cell with a single exit. Instead, the path winds 5 steps (R6C6 → R7C6 → R7C7 → R6C7 → R5C7 → R5C6) to sweep those cells before landing on 18.
Head at R6C6; outlined cells are the ones this deduction uses.
Show the forced path continuation
4. Touching the Border Can Split the Board (8×8 hard)
With the head at R7C6, stepping to the border cell R8C6 would divide the empty cells into 2 separate groups, including the 4 cells R7C7, R8C7, R7C8, R8C8. The path cannot cross itself, so once it enters one group it can never reach the other. R8C6 is ruled out, and the solution continues to R7C7.
Head at R7C6; outlined cells are the ones this deduction uses.
Show the forced path continuation
Complete 6×6 walkthrough: from 1 to 13
This complete solve follows 6×6 Easy #1 from the first cell to the final number (13). For each stretch between two clues, an exhaustive search tried every route that avoids other clues; the counts below come from that search. Rows are numbered R1–R6 from top to bottom and columns C1–C6 from left to right.
Starting grid: 1 sits at R3C1 and the path must end at 13 (R1C6) after visiting all 36 cells.
Step 1: Clue 1 to Clue 2 (R3C1 → R4C1 → R5C1 → R6C1 → R6C2 → R5C2)
Of the 6 routes from 1 to 2 that avoid other clues, 3 leave an empty cell with a single exit, 2 run out of moves further on. Only R3C1 → R4C1 → R5C1 → R6C1 → R6C2 → R5C2 can still finish the board.
Show board after reaching 2
Step 2: Clue 2 to Clue 3 (R5C2 → R5C3)
R5C2 → R5C3 is the only way from 2 to 3 that avoids every other clue and visited cell.
Show board after reaching 3
Step 3: Clue 3 to Clue 4 (R5C3 → R6C3 → R6C4 → R5C4 → R4C4)
Of the 8 routes from 3 to 4 that avoid other clues, 4 cut the empty cells into separate groups, 3 leave an empty cell with a single exit. Only R5C3 → R6C3 → R6C4 → R5C4 → R4C4 can still finish the board.
Show board after reaching 4
Step 4: Clue 4 to Clue 5 (R4C4 → R4C5 → R5C5 → R6C5)
Of the 6 routes from 4 to 5 that avoid other clues, 4 cut the empty cells into separate groups, 1 leaves an empty cell with a single exit. Only R4C4 → R4C5 → R5C5 → R6C5 can still finish the board.
Show board after reaching 5
Step 5: Clue 5 to Clue 6 (R6C5 → R6C6 → R5C6 → R4C6 → R3C6 → R3C5 → R3C4)
R6C5 → R6C6 → R5C6 → R4C6 → R3C6 → R3C5 → R3C4 is the only way from 5 to 6 that avoids every other clue and visited cell.
Show board after reaching 6
Step 6: Clue 6 to Clue 7 (R3C4 → R3C3 → R4C3)
Of the 2 routes from 6 to 7 that avoid other clues, 1 leaves an empty cell with a single exit. Only R3C4 → R3C3 → R4C3 can still finish the board.
Show board after reaching 7
Step 7: Clue 7 to Clue 8 (R4C3 → R4C2 → R3C2 → R2C2)
R4C3 → R4C2 → R3C2 → R2C2 is the only way from 7 to 8 that avoids every other clue and visited cell.
Show board after reaching 8
Step 8: Clue 8 to Clue 9 (R2C2 → R2C1 → R1C1 → R1C2)
Of the 3 routes from 8 to 9 that avoid other clues, 2 cut the empty cells into separate groups. Only R2C2 → R2C1 → R1C1 → R1C2 can still finish the board.
Show board after reaching 9
Step 9: Clue 9 to Clue 10 (R1C2 → R1C3 → R2C3 → R2C4)
Of the 2 routes from 9 to 10 that avoid other clues, 1 cuts the empty cells into separate groups. Only R1C2 → R1C3 → R2C3 → R2C4 can still finish the board.
Show board after reaching 10
Step 10: Clue 10 to Clue 11 (R2C4 → R1C4 → R1C5 → R2C5)
Of the 2 routes from 10 to 11 that avoid other clues, 1 leaves an empty cell with a single exit. Only R2C4 → R1C4 → R1C5 → R2C5 can still finish the board.
Show board after reaching 11
Step 11: Clue 11 to Clue 12 (R2C5 → R2C6)
R2C5 → R2C6 is the only way from 11 to 12 that avoids every other clue and visited cell.
Show board after reaching 12
Step 12: Clue 12 to Clue 13 (R2C6 → R1C6)
R2C6 → R1C6 is the only way from 12 to 13 that avoids every other clue and visited cell.
Show board after reaching 13
Advanced technique: checkerboard parity on 7×7 and 8×8 grids
Imagine colouring the grid in alternating light and dark squares like a chessboard. Because diagonal moves are forbidden, every step along the Zip path switches square colour:
- Same colour endpoints: Reaching a cell of the same colour requires an even number of steps (2, 4, 6…), which covers an odd number of intermediate cells.
- Opposite colour endpoints: Reaching a cell of the opposite colour requires an odd number of steps (1, 3, 5…), covering an even number of intermediate cells.
- Odd-sized grids (7×7): A 7×7 board has 49 cells—25 of the corner colour and 24 of the other. Every full-board Hamiltonian path on a 7×7 grid must start and end on the corner colour.
Want to compare how Zip differs from multi-pair path games? Read Zip vs Numberlink: Hamiltonian Paths and Pair Connections, or try Queens and Tango.
FAQ
How do you start a Zip puzzle without guessing?
Begin by inspecting the four corners and the cells around number 1 and the highest number. Any unnumbered corner has only two orthogonal neighbours, so the path must enter through one and leave through the other. Mark forced corner turns and dead-end corridors before choosing between open interior routes.
Can the path visit the final number early?
No. Because a Zip path must cover every cell on the board and end on the highest number, stepping onto the final number while any other cell remains empty immediately traps the path. The final number is the only cell allowed to have a single available neighbour.
Why do two adjacent numbers sometimes take a long detour?
If stepping directly from k to an adjacent k+1 leaves an unnumbered pocket of cells with only one way in and no way out, the direct step is illegal. The path must sweep through the pocket first and land on k+1 at the end of the detour.
What is the checkerboard parity trick in Zip?
Colour the grid like a chessboard. Every orthogonal step changes colour. If two consecutive numbers sit on the same colour, any path between them must take an even number of steps (covering an odd number of unnumbered cells in between). That parity check quickly rules out impossible detours on hard 8×8 boards.