Picture a full set of dominoes packed into a rectangle. Someone copied down every number and then cleared the tiles away. Dominosa Domino Logic unblocked hands you that sheet of numbers and asks you to put the set back exactly as it was.
This is the Dominosa puzzle from Simon Tatham's Portable Puzzle Collection. Each puzzle has one answer, and you reach it with careful logic, not lucky guesses.
How to play Dominosa Domino Logic
In the standard size the numbers run from 0 to 6, which gives 28 dominoes, including doubles such as 2-2. They fill an 8 by 7 grid. Every domino covers two squares that touch across or up and down.
Click the edge between two numbers to lay a domino over them, and click again to remove it. Right-click an edge to draw a short line that means no domino goes there. These marks are for your own notes and help a lot on bigger grids.
The puzzle is done once the grid is fully tiled with no repeated pair. If you place a duplicate, both copies turn red. The Type menu sets the size of the number range and how much deduction the puzzle demands.
Controls
| To… | Keyboard | Mouse | Touch |
|---|---|---|---|
| Place or remove a domino | Arrow keys to a spot between two numbers, then Enter | Left-click between two neighboring numbers | Tap between two neighboring numbers |
| Draw or erase a "no domino here" line | Space | Right-click between two numbers | Press and hold between two numbers |
| Highlight every copy of a number | Type the number | Right-click on the number | Press and hold on the number |
| Undo, redo, new puzzle | U / R / N | Undo move, Redo move and New game buttons | Undo move, Redo move and New game buttons |
Tips
- Hunt for pairs that occur once. If 3 and 5 sit next to each other in only one place on the whole grid, the 3-5 domino has to go there.
- Fill in forced corners. A square with only one open neighbor has no choice. Lay that domino and look at what it blocks.
- Rule out repeats. After you lay a given pair, every other spot showing the same two numbers gets a line. That often creates new forced moves.
- Highlight a number. Typing a digit or right-clicking it lights up every copy, which makes the rarer pairs easier to spot.
- Start on Basic. Hard and Extreme need chains of reasoning, so warm up on the easier settings before stepping up.
Dominosa Domino Logic questions
What are the difficulty settings?
Trivial, Basic, Hard and Extreme change how advanced the reasoning has to be. All of them have a single correct answer.
Can I play it with just a keyboard?
Yes. Steer the cursor using the arrows, then Enter adds or lifts a domino while Space toggles a line. U, R and N undo, redo and start a new puzzle.
How do I mark an edge on a touch screen?
Press and hold between two numbers to draw or erase a line. A quick tap places a domino there instead.
