How to solve Zip

How to solve Zip: techniques that work

Zip is a Hamiltonian path puzzle: one line from checkpoint 1 to the last number that visits every cell exactly once. Before drawing anything, look at the corners and edges. A corner cell has only two neighbours, so the path must enter through one and leave through the other — corners are effectively pre-drawn.

Watch for pockets. If your planned route walls off a group of empty cells, the board is already lost — every cell must be reachable by the remaining path. Good players constantly ask "can the line still get back out of there?" before committing to a turn.

Use the checkpoints as anchors and plan backwards from the final number as well as forwards from 1. The stretch between the two last checkpoints is usually the most constrained part of the board; solving it mentally first often decides the whole route. Walls block movement between adjacent cells, which paradoxically helps: each wall removes options and makes more of the path forced.

Common mistakes

The most frequent one is filling space greedily and leaving a single unreachable cell in a corner — the parity of the grid means one stranded cell can rarely be recovered. Undo early rather than pushing a doomed line.

Second: forgetting the checkpoints must be hit in ascending order. A route that touches 3 before 2 is invalid even if it covers the board perfectly.

From easy to hard

Difficulty scales with board size, wall count and checkpoint spacing. On hard boards, treat each pair of consecutive checkpoints as its own mini-puzzle and check that your segment leaves a connected region for the rest of the path.