How to Play Zip Game Unlimited: Rules and Tips

The goal: one line through every cell

Each Zip board is a square grid with a few numbered dots on it. Your job is to draw one continuous line that starts on the 1, passes the numbers in order, and finishes on the highest number. By the time you finish, the line has to have covered every cell of the grid exactly once.

There is no score. A board is solved the moment the last empty cell is filled and the line ends on the last number, and the only number you chase is your time.

Seven rules, in the order you meet them

Start on the 1. The line begins there, and on a fresh board that cell is already drawn.
Move one cell at a time. Up, down, left or right. There are no diagonal steps.
Meet the numbers in order. After the 1 comes the 2, then the 3, and so on.
Use every cell once. The line may not cross itself or visit a cell twice.
Respect the walls. On Hard boards, hedge walls sit between some neighboring cells and the line cannot pass through them.
Finish on the last number. It is the end of the line, not a stop along the way.
Fill the whole grid. A line that reaches the last number with empty cells left over is not a solution.

Reaching the last number is easy. Reaching it after visiting everything else is the puzzle.

Three board sizes, from 5 by 5 to 7 by 7

The game has three levels. Easy is a 5 by 5 grid, 25 cells, with 6 numbers. Medium is 6 by 6, 36 cells, with 8 numbers. Hard is 7 by 7, 49 cells, with 10 numbers and 6 hedge walls.

On every level the numbers sit about five steps apart along the finished line, on average. So the cell that holds the 4 is usually a short walk from the 3, not a long one. Start on Easy if the idea is new.

Hedge walls on Hard boards

Hedges only appear on Hard. Each one sits on the edge between two cells that touch, and the line cannot step across it. A wall also works the other way: it tells you that those two cells are not next to each other on the line.

Every board is built around a line that already exists, and walls are only placed on edges that line never uses. So a wall never makes a board impossible. If a Hard board looks stuck, the problem is your line, not the walls. A wall beside a cell with few open sides can settle which way the line has to turn.

Drag, tap or type: ways to draw the line

You can draw the line three ways, and they mix freely.

Drag. Press on the 1 (or on the end of the line) and move through the cells. Each cell you enter becomes the next step. Entering the cell you just left takes a step back, and entering an older cell of the line cuts the line back to it.
Tap. Tap a cell that touches the end of the line to step there. Tap a cell that is already on the line to cut back to it. Tapping the 1 starts over.
Keyboard. Focus the board, then use the arrow keys to move the end of the line. Backspace takes one step back, and Delete clears the line down to the 1.

A Clear button does the same as Delete and never counts as a hint. The clock starts with your first move, not when the board appears.

Why the game refuses some moves

This version will not let you build an illegal line. If a tap or key press breaks a rule, the end of the line shakes and nothing changes; while you drag, cells that do not touch the end are simply skipped. There are four reasons.

Too far. The cell you chose does not touch the end of the line.
Wall. A hedge sits between the end of the line and that cell.
Wrong number. You tried to step on a number that is not next. The 4 cannot be visited before the 3.
Too early. You tried to step on the last number while empty cells remain. The last number only closes the line, once every other cell is covered.

The last refusal catches new players. It is deliberate: it stops one stray tap from driving the line into a dead end.

A worked example on an Easy board

Here is a real Easy board, the one with the puzzle number E-0000. You can load it by adding ?p=E-0000 to the address of the Zip page. Dots show empty cells.

. . 3 . 6
. . 4 . .
. 2 . . .
. 1 . 5 .
. . . . .

Start with the four corners. The top-right corner holds the 6, the last number, so the line ends there. The other three corners are empty, and an empty corner has only two neighbors. The line has to enter one and leave through the other, which means it uses both of its edges. So the line passes through the top-left corner from the cell on its right to the cell below it. The same holds in the bottom-left and bottom-right corners. Three cells of the line are fixed before you draw anything.

Next, look at the 1. It has four neighbors, and the cell above it is the 2. The line can open by stepping up onto the 2, down, or right. It never opens to the left: in every valid line, that cell is already joined to the cell above it and to the bottom-left corner, so it cannot also touch the 1.

A computer search of this board finds 7 valid lines, and all of them cross the three empty corners as described above. Here is one of the seven, with each cell numbered by the step that visits it:

 9 10 11 12 25
 8  7 14 13 24
 5  6 15 22 23
 4  1 16 21 20
 3  2 17 18 19

The board's numbers 1 to 6 are visited at steps 1, 6, 11, 14, 21 and 25. That is the whole pattern: find what the corners force, see which openings survive, and let the numbers decide the rest.

Corners and edges: where to start thinking

Before you draw, look at the cells with the fewest open sides. It is the habit that pays off most.

A corner has two neighbors. Unless it holds the 1 or the last number, both edges are on the line.
A cell with only one open neighbor has to be the start or the end of the line.
An edge cell has three neighbors, and unless it holds the 1 or the last number, the line uses two of them. If one is already taken, the choice is made for you.

Work from these forced cells inward.

Planning around the numbers

Because the numbers must come in order, they cut the line into short stretches: 1 to 2, 2 to 3, and so on. Ask which cells can belong to which stretch.

Look at the last number as well as the first. The line ends there, and the game will not let you step on it early, so the cells around it tell you how the line must arrive. Plan the route in from the end as often as the route out from the 1.

Do not rush at the next number. A line that goes straight at the 2 can leave an empty pocket that the rest of the line can no longer reach. Fill pockets while the line is still near them.

Backing out of a dead end

The usual sign of a dead end is an empty cell with no free neighbor left, or a block of empty cells the end of the line cannot reach. When that happens, back up. Dragging back along the line undoes one step at a time, and Backspace does the same. Return to the last real choice and try the other option. If the whole line feels wrong, press Delete or Clear and start from the 1. Boards are small, so a restart is cheap.

A board may have several answers. This version only checks the rules, so any line that fills every cell and meets the numbers in order wins.

When a hint is worth taking

Each press of Hint draws the next correct cell of the line. If your own line has wandered off the route the game stored, it is first cut back to the point where it still matches, and then one more cell is added. So a hint also shows where you went wrong.

After three hints a Show answer button appears. A board where you showed the answer does not count toward your streak or your best time. Try one hint before Show answer: a single cell is often enough to unlock the rest.

Daily boards and unlimited boards

Zip has two modes. Unlimited gives you a new board each time you press Next puzzle, made in your browser at once, at the level you picked. There are about a million numbered boards per level, so repeats are rare. Daily gives the board for today's date, taken from your own device, so players on the same date get the same one.

Your best time for each level and your daily streak are stored in the browser, with no account, and only Daily boards add to the streak. To send a friend a specific board, share the address: it carries the puzzle number after ?p=, as in the example above.

If you like this kind of reasoning, Queens with no daily limit asks you to place one queen in every row, column and region, with none touching, and Tango boards with no daily limit ask for equal counts of two symbols in every line, never three in a row. For a different skill, read how to judge sizes by eye in Size It Up, or browse daily games with no daily limit.

A note on where this version comes from

The idea of a one-line path puzzle is not ours. This version is independent and not affiliated with the game that inspired it. We wrote the board generator and the page ourselves, and how our puzzles are made explains how boards are built and checked.

Try an Easy board first. The corner habit that solves 5 by 5 carries you up to 7 by 7.