Triangles rules: how to play the dot game
The goal
Claim more triangles than your opponent. You claim a triangle by drawing the third and final line around it, and closing a triangle earns you another turn, so one good move can turn into a whole run of points. When every line on the board has been drawn, the player with the most triangles wins.
At a glance
- Players
- Two: you against the computer, or a friend on the same device or online.
- Board
- 16 dots in a 4 × 4 grid, forming 9 small squares.
- Lines
- 42 in total: 12 horizontal, 12 vertical and 18 diagonal.
- Triangles
- 36 to claim, four in every small square.
- Extra turn
- Yes, every time your line closes a triangle.
- Game ends
- When all 42 lines have been drawn.
How to play
The board
The board is a square of 16 dots, four rows of four. Any two neighboring dots can be joined by a line: left to right, top to bottom, or corner to corner across one of the nine small squares. Each small square has two diagonals and you may draw both. They cross in the middle, but there is no dot there, so the crossing point never counts as a corner. At the start of the game, all 42 possible lines are shown faintly.
Taking a turn
On your turn, draw exactly one line between two neighboring dots that are not joined yet. In the game on this site you click one of the faint lines. You cannot pass, and a line never runs past a dot to a farther one.
What counts as a triangle
A triangle is three dots joined by three drawn lines. On this board every triangle is exactly half of one small square: two of the square’s sides plus one of its diagonals. In other words, each triangle is made of one horizontal line, one vertical line and one diagonal. Every square contains four triangles, one in each corner, and they overlap. That is why nine squares hold 36 triangles.
All 6 lines
Top left
Top right
Bottom left
Bottom right
Scoring a triangle
When you draw the line that closes a triangle, that triangle is yours: it is shaded in your color and adds one point to your score, no matter who drew its other two lines. A single line can close several triangles at once and be worth up to four points.
Extra turns
Closing a triangle earns you another turn. As long as each new line closes something, you keep going. As soon as you draw a line that closes nothing, the turn passes to your opponent.
How the game ends
The game ends when all 42 lines have been drawn. By then all 36 triangles have been claimed, and the player with more of them wins. An 18–18 tie is possible. The last line of the game always closes at least two triangles, so the final move always scores.
Playing Triangles on this site
Against the computer
Choose Play the computer for a quick single-player game, on Easy or Hard. You move first in the first game and the first move alternates after that. The first player draws in cream, the second in red.
On Hard, the computer takes every triangle you leave open, avoids handing you one while it still can, and when it has to give some away it gives as few as it can. On Easy it sometimes draws a random line instead. Press New game to start over at any time.
To play a friend on one device, set Opponent to Friend on this device and take turns.
Online with a friend
- 1Choose Play with friends and type your name.
- 2Press Start a table and send the invite link, or the six-character table code, to your friend.
- 3Your friend opens the link, or enters a name and the code under Join a table.
- 4When both names are listed, the host presses Start the game. The host draws in cream and moves first.
- 5After the game, both players press Play again; the other player moves first.
Triangles vs Dots and Boxes
If you have played Dots and Boxes, you already know most of Triangles. The two games share the same core: players take turns drawing one line, whoever closes a shape claims it, closing a shape earns another turn, and the most shapes wins. The differences all come from the diagonals.
| Dots and Boxes | Triangles (this site) | |
|---|---|---|
| Lines you can draw | Horizontal and vertical | Horizontal, vertical and diagonal |
| Shape you score | A box (4 lines) | A triangle (3 lines) |
| Shapes each line belongs to | 1 or 2 | 2 or 4 |
| Do shapes overlap? | No | Yes, four triangles per square |
Because a triangle needs only three lines, the board gets dangerous much sooner than in Dots and Boxes: the moment a triangle has two of its lines, the next player can take it. Some pencil-and-paper versions of the triangle game use a triangular grid of dots. Ours keeps the familiar square grid and adds the diagonals, so every triangle is half of a small square. For how this changes the tactics, see the Triangles strategy guide.
Common questions
- Do you get another turn after completing a triangle?
- Yes. If your line closes at least one triangle, you draw again. It is one extra turn however many triangles that line closed, but there is no limit on how many times in a row it can happen.
- Can one line complete more than one triangle?
- Yes, up to four. A diagonal or a side on the edge of the board is part of two triangles. A side in the middle of the board is part of four, two in each of the squares it separates.
- Does it matter who drew the other two lines?
- No. Lines do not belong to anyone. A triangle goes to the player who draws its third line, even if both of the other lines were drawn by the opponent. The line colors only show who drew each line.
- Can you draw both diagonals in the same square?
- Yes. The two diagonals cross in the middle of the square, but there is no dot there, so the crossing point is not a corner and does not create extra, smaller triangles.
- Can you pass, or refuse to take a triangle?
- You cannot pass: every turn you must draw one line. You are never forced to close a triangle, though. You may draw any open line, even when a triangle is waiting to be taken.
- Can Triangles end in a tie?
- Yes. There are 36 triangles on the board, so if both players finish with 18 the game is a tie.
Ready to play?
Play against the computer, with a friend on the same device, or send a link and play a friend online. No download or sign-up needed.