Colour Lines

Five pairs of marked dots sit on a five-by-five board. Draw a line joining each pair so that no two lines cross and, between them, the lines cover all twenty-five squares. Every square you draw, retrace or cut spends one move from a budget the solver worked out before you started.

It runs entirely on your device: 0 network requests, works offline. No ads, no account, nothing to buy, and no betting, money or prizes of any kind.

1. Focus the board — click it, or press Tab until it is focused.
2. Move the cursor with the arrow keys. With the pen up this is free; it costs nothing to look.
3. Start a line by moving onto one of its dots and pressing Enter. The pen is now down, and the square you are on is the live end.
4. Draw with the arrow keys. Each step takes the line into the next square and costs one move. Stepping back the way you came retraces the line — that costs a move too.
5. Join the pair by stepping onto the line's other dot. The pen lifts by itself.
6. Lift the pen with Enter on the live end, or Esc anywhere. Lifting is free.
7. Start again by pressing Enter on either of a line's dots. That rubs the whole line out and costs one move — it is the cheapest way to undo a line you have got wrong.
8. Win when all five pairs are joined and every one of the twenty-five squares carries a line. Joining the pairs is not enough on its own; the status row counts both.

Each pair has its own shape — circle, triangle, square, diamond, star — printed on its dots and on every square its line covers, so the board is readable in greyscale, in print, and with any kind of colour vision.

How do you solve a connect-the-pairs grid puzzle?

Start at the corners, not in the middle. A corner square has only two neighbours, so whichever line passes through it must enter by one and leave by the other — which fixes two of that line's squares before you have drawn anything. If a corner is itself a dot, the line leaving it has only two choices. Edge squares are next: they have three neighbours instead of four, so they constrain far more than the middle does. Then use the covering rule as a tool rather than a chore: any empty square whose free neighbours have dropped to two is forced in exactly the same way a corner is, and a pocket of empty squares that no remaining line could reach tells you a line you have already drawn is wrong. Work the forced squares until the middle has nowhere left to go.

Is every board actually solvable?

Yes, and by construction rather than by hope. The generator builds the answer first: it starts with twenty-five one-square lines — a trivial cover of the board — and repeatedly welds two of them together at adjacent ends until five remain. Welding two non-touching lines end to end gives another non-touching line, and no square is ever dropped, so "these lines are separate and cover everything" is true at every step. The puzzle you see is those five lines with their middles rubbed out, so a full solution existed before the question did.

Is there more than one right answer?

No. Existence is not enough — a board with two answers is one you can be marked wrong for solving. After drawing a layout the generator runs an exhaustive search that counts full covers and stops at two, and throws the layout away if it finds a second one. It draws again, up to forty times, so what reaches you has exactly one answer.

Why is there a move budget?

Because without one the game is "drag every line around until something fits", which is not a puzzle. Twenty-five is the floor and not a guess: every square has to be drawn exactly once, and drawing a square costs one move whether it starts a line or continues one. On top of that you get a fixed margin plus an extra move for every three blind alleys the solver had to back out of on this particular board — so a tangled board is given more room, because the solver proved it needed it.

Is there any money, betting or in-app purchase in this?

None, and there never will be. No currency, nothing to buy, no lives to refill, no wager of any kind. It is a puzzle and a move budget, and that is the whole game.

What happens if I draw through a line I have already drawn?

It gets cut back to the square you took, exactly as if you had rubbed out everything past that point. Its dots stay where they are — dots never move, and drawing onto another line's dot is simply refused. Refusals are free; only a square actually drawn, retraced or cut spends a move.

Does it work offline, and can I play it with a keyboard or a screen reader?

Yes to all three. Once the page has loaded once, the whole game is on your device and no server is involved in play at any point. Arrows move and draw, Enter starts and stops a line, Esc lifts the pen, and the board publishes a row-and-column description that names each square in words — "square line", "star dot, joined", "empty" — so nothing depends on telling hues apart.

Five by five, twenty-five squares, five pairs, and lines of at least three squares each. The budget runs from thirty-nine to forty-five moves depending on how much blind alley the solver found. The generator gives itself forty draws to find a board with exactly one answer; if every draw were ambiguous it would fall back to a hand-checked layout that a test proves is unique, so the worst case is still a fair board.

Pipe Flow rotates tiles until one route connects two fixed points, which is the same connectivity idea with the pieces fixed and their orientation free. Fence Loop draws a single closed loop instead of five open ones. Grid Clues fills squares from counts rather than from routes, and Mirror Maze routes a single beam through squares you place yourself.

Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.