Zip is a path puzzle. Draw a single line that starts at 1, passes every number in order and fills every cell of the grid exactly once. Walls block the way. Each board has one solution.
A corner cell has only two neighbours. Unless it is the start or the end, the line must enter through one and leave through the other.
A cell with only two open neighbours is forced in the same way. Walls create many of these.
If your line splits the empty cells into two separate areas, at least one of them can no longer be filled. Back up at once.
Look at how many cells lie between two numbers and how far apart they are. A short gap with a long distance tells you the path runs straight.
The last number is the end of the line. Tracing back from it often settles the final part of the board.
Pocket Logic gives you a fresh Zip board every day, the same for every player, with a streak, best times and smart hints. Hundreds of extra levels grow from warm-up to expert, and every board has exactly one solution. It works offline on Android and is free to play.
Draw one continuous line from 1 to the last number, visiting the numbers in order and filling every cell of the grid once.
Pocket Logic for Android has a daily Zip board, the same for every player, plus levels that grow from small warm-ups to large expert grids.
In Pocket Logic you drag back along the line to undo steps, and the undo button takes back any move.