How to play Mòpyon (five in a row)

Mòpyon is the pen-and-paper duel that generations of Haitian students played in the back of their school notebooks. The rules fit in one sentence: two players take turns placing their mark, and the first to line up five marks in a row wins. Everything else on this page explains the details and the small rules that make online games fair.

The board

On Mòpyon.net the game is played on a 15 × 15 grid, the size used for most five-in-a-row games around the world. Marks go on the crossings of the lines, not inside the squares. A notebook grid works exactly the same way, which is why you can play a real game with nothing more than a pen and a page of squared paper.

The players

One player uses X (drawn in red on our board) and the other uses O (drawn in blue). X always plays first. After that the players alternate, one mark per turn. A mark can never be moved or erased once it is placed.

How to win

You win the moment you have five of your marks in an unbroken line: across, down, or along either diagonal. On Mòpyon.net a line of six or more also counts as a win, so you never have to worry about making a line that is “too long”.

X has five in a row across the middle and wins the game.

Diagonal lines are just as strong as straight ones, and they are the ones beginners miss most often. Before every move, look along all four directions from the last mark your opponent played.

A diagonal five counts the same as a straight one.

When the game ends without a winner

If every crossing is filled and nobody has five, the game is a draw. In practice this almost never happens on a 15 × 15 board. Players can also agree to a draw at any moment: one player offers, the other accepts or refuses.

Resigning, time and leaving

Resign (“Fè lach”) ends the game at once and counts as a loss.
In a timed game, each player has a clock. If your clock reaches zero, you lose on time. Most of our time controls add a few seconds back after each move (this is called an increment).
If you stop moving for too long, or leave the game and don’t come back within 20 seconds, the game is lost.

Rated and casual games

Games against other people online can be rated: winning raises your rating and losing lowers it, by an amount that depends on how strong your opponent is. Games against the computer, puzzles and pass-and-play games on one phone never change your rating, so they are the best place to practise.

Is there an advantage for X?

Yes. Mathematicians showed in the 1990s that, with perfect play, the first player can always force a win in free five-in-a-row on a 15 × 15 board. That proof needed huge computer searches, so it changes nothing for real games between people: the advantage is small, and mistakes decide almost every game. Rated games give each player X and O equally often over time.

Where to go next

Once the rules are clear, the real game is about threats: open threes, fours and double threats. Our strategy guides explain them one at a time, with diagrams, starting with the open three.