Four in a row strategy: the middle column, threats and odd rows

Own the middle

A disc in the middle column can be part of more lines of four than a disc in any other column: across, down and both diagonals. The 1988 solutions by James Dow Allen and Victor Allis showed that opening in the middle is the only first move that wins against perfect defense.

Keep taking the middle and the columns next to it early. Edge columns take part in very few lines.

Build threats, not lines

A threat is three of your discs in a line with the fourth space empty. A threat whose empty space sits right on top of a disc can be played at once; one that floats higher waits until the column fills up to it.

Two threats at once usually win. Your rival can block only one of them.

Never play under a threat

If your rival has a threat waiting in a column, the disc you drop just below it lets them win on top. Late in the game, when every other column is full, someone is forced to play there. That is called zugzwang, and it decides most close games between strong players.

The odd and even row rule

Count rows from the bottom, 1 to 6. Because the board has an even number of spaces, the order of moves at the end fills columns in a predictable way.

• The first player wants threats on odd rows: 1, 3 and 5.
• The second player wants threats on even rows: 2, 4 and 6.
• A threat on your good row tends to become playable on your turn as the board fills.

Sources

• James Dow Allen, who announced the first solution in 1988, and L. Victor Allis, master's thesis, Vrije Universiteit Amsterdam, 1988, on the solved game and the odd and even row rules

Back to the four in a row rules

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