Put one diagonal in each square, satisfy the numbered corners, and keep every chain of lines open to the edge.
Slant Diagonals is a quiet pen-and-paper style puzzle where your only tool is a slanted line. Each square on the grid must end up holding one diagonal, tilted either toward the top-left or the top-right. Small circled numbers sit on the grid points, and each one says how many lines must touch that exact point.
There is one more rule, and it shapes the whole puzzle. The lines you draw may never join up into a closed shape of any size. Every path has to run out to the border instead.
The goal
You win by filling the whole board so that every number is matched and not a single loop appears. A clue in the open middle of the grid can touch up to four squares, so its number runs from 0 to 4. A clue on the border only touches two squares, and a clue sitting in a grid corner meets a single square.
That limit is useful. A middle 0 would force four lines to bend away and form a tiny diamond, which is a loop, so you will only ever find a 0 on the edge.
How the controls feel
With a mouse, a left click puts a backslash line in a square and a right click puts a forward slash. Clicking again moves the square to the other slant and then back to empty, so one button can reach every state. On a keyboard, move with the arrow keys and press Enter or Space, or type the slash keys to set a direction directly. Backspace empties a square, and N, U and R start a new game, undo and redo.
Touch works too. Tap to cycle, press and hold for the other slant, or flip the tap switch below the grid.
Strategy notes
- Begin with any 4 and any 0. Each of those locks in every square around it.
- Edge clues of 0 or 2 decide both of their squares at once.
- After you place a line, look at both of its ends. It may have just finished a clue, which pushes the rest of that clue’s squares to lean away.
- When you see three sides of a small diamond, the last square must tilt the other way.
- Once a clue has all the lines it needs, every open square around it points away from it.
Good to know
Mistakes are easy to spot because the game colors any loop and any clue that can no longer be met. The presets cover 5x5, 8x8 and 12x10 grids, each at Easy or Hard, and you can also set a custom size. If you prefer the mouse buttons the other way around, Preferences lets you swap them. This puzzle comes from Simon Tatham’s collection, where it is called Slant.
Controls
| Action | Keyboard | Mouse | Touch |
|---|---|---|---|
| Place or cycle a \ line | Arrow keys to move, then Enter | Left-click a square | Tap a square with Tap set to "\ first" |
| Place or cycle a / line | Space | Right-click a square | Press and hold, or set Tap to "/ first" and tap |
| Set a square to one direction directly / empty it | Type / or \ / Backspace | — | — |
| New game, undo, redo | N, U, R | Menu buttons above the grid | Menu buttons above the grid |
Slant Diagonals FAQ
Can I play Slant Diagonals on a phone or Chromebook?
Yes. It runs in the browser with mouse, keyboard or touch. On a touchscreen, a tap cycles a square and a press and hold starts from the opposite slant. A switch under the grid lets you choose which direction a tap places first.
How do I know when the puzzle is solved?
Every square needs a line, every corner number must be met exactly, and no loop may exist anywhere. Once all three are true, the board gives a quick flash. Until then, broken clues and closed loops show up in a warning color.
Which grid size should a beginner pick?
Start with 5x5 on Easy. It teaches the basic patterns fast. The 8x8 and 12x10 presets take longer, and the Hard setting expects you to think about how two neighboring squares depend on each other. Custom sizes are also available.
What if I get stuck halfway through?
Undo and redo have no limit, so you can back up to the last move you were sure of. Look again at any number that is one line short. If you just want to see the answer, the Solve option fills in the grid.
