Zip Tips: Walls, Dead Ends and the Right Path

Before extending a Zip path, check what the move leaves behind. A line can reach the next number and still cut off cells that must be visited later.

You need one path from 1 to the largest number, visiting every cell once and meeting the numbers in order. Walls block movement between neighboring cells. The practice diagrams below are separate examples. Count rows from the top and columns from the left.

A route to 2 can still be wrong

Look at the five empty squares along the top row in this example. The line started at the top-left corner, moved down, then crossed the whole second row. Its head is now below that row. Every route back to those five squares passes through a cell already used by the line.

Reaching 2 didn't rescue the move. The branch needs to be undone far enough to leave an entrance to the top row. On this board, going right from 1 allows those cells to be visited before the path moves down.

Find where a wall actually ends

The black wall below separates columns 3 and 4 in the first four rows. Moving between those columns in row 4 would cross it. The blue line instead reaches row 6 before crossing, below the end of the wall.

That is a legal detour, not a rule that every path must hug a wall. Other cells and numbered checkpoints decide the route. Trace the exact shared edge between two squares before drawing across it; a thin grid line isn't a wall.

When a corridor belongs at the end

Here the bottom row has only one entrance: the rightmost square can be reached from above. The largest number, 3, is at the other end. Once the line enters, it must continue left through the row and finish at 3. It can't leave the strip and return without using a square twice.

This corridor belongs at the end because it contains the finish and has just that one entrance. A corridor with two open ends can be a passage through the middle of a solution. Don't reserve every narrow strip for later; count its openings and check the numbered order.

Check both neighbors of a corner

A corner normally has two neighbors. Being in a corner alone doesn't tell you which one the line must come from.

In this position, the wall immediately left of 3 blocks one of those neighbors. The last move must therefore come from the square above. The short blue segment shows that ending planned backward; the path you draw during play still starts at 1.

Stop at a real dead end

The head in the top-right corner below has no unused neighbor. The cell on its left and the cell below it already belong to the path, while most of the board remains empty. There is no next move.

Drag back along the line or tap an earlier cell to shorten it. Back up to the choice that closed the route. Removing just the last square may leave the same branch trapped.

Check numbered cells as well as empty ones. You can't pass through 5 while still looking for 4, and reaching the final number with cells unvisited doesn't complete the board. A move must preserve a route through all the remaining cells in the required order.