Range Shading Puzzle
Range Shading Puzzle is a grid of numbers where your only tool is black paint. Each number tells you how far it can see, and your shading has to make every view come out exactly right.
The puzzle, called Range in Simon Tatham's Portable Puzzle Collection, was contributed by Jonas Kölker. It runs in a browser tab with nothing to install, so it is easy to open on a Chromebook between classes.
How to play Range Shading Puzzle
A number counts itself plus every white square it can see straight up, down, left and right. Sight stops at a black square or the edge. So a 3 might see one square to its left, one above, and nothing else.
Three more rules apply. Numbered squares stay white. Black squares may meet at a corner but never side by side. And all the white squares have to form one connected area.
Left-click shades a square; right-click drops a dot meaning "this stays white." Clicking again cycles through black, dot and blank. On touch screens, use the Tap switch to choose what a tap does. The grid flashes when it is complete.
Controls
| Action | Keyboard | Mouse | Touch |
|---|---|---|---|
| Shade a square (repeat to cycle) | Arrow keys, then Enter | Left-click | Tap with Tap set to shade |
| Mark a square white with a dot | Space | Right-click | Press and hold, or set Tap to dot |
| Dot every square you pass | Shift + arrow keys | — | — |
| New puzzle, undo, redo | N, U, R | Buttons in the menu bar | Buttons in the menu bar |
Tips
- Total up how far a number could possibly see. If that maximum equals its value, every square in its row and column view must stay white.
- The moment you shade a square, dot all four of its side neighbors. Black squares can never touch, so those are guaranteed white.
- Low numbers are tight. A 2 can view only a single neighbor beyond itself, so three of its four directions must be blocked right away by black or the border.
- Before you shade near a wall or corner, check that the white area stays joined. A black square that cuts off a white pocket is always a mistake.
- When two numbers share a line, one black square limits both views at once, so count from each end.
If you like Range Shading Puzzle, try these
Skyscraper SightlinesSightline counting returns in a city grid, where towers of different heights block views instead of black squares.
Unruly Black and WhiteShading cells black or white stays the task, but rows must balance and no three of one color may line up.
Questions
What do the numbers mean in Range?
Each number is the count of white squares visible from it in the four straight directions, including the numbered square itself. Black squares and the board edge block the view.
Can I play Range Shading Puzzle on a phone?
Yes. Tap to shade, or press and hold to place a dot. A Tap switch below the grid lets you make plain taps place dots instead.
Is there a hint or solve option?
The menu bar has a Solve button that shows the finished grid. Undo steps back from it if you would rather keep solving.
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