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4x4
Board · Classics · plays in your browser, no download
Drop a disc into a column, it falls to the lowest free slot, and you are trying to line up four. A game simple enough to explain to a child and deep enough that it took a computer to settle.
Where it comes from
Four in a row is a board game with one rule and one complication: you choose a column, not a square, and the counter falls to the bottom. It has existed forever as a pencil-and-paper game, and since the seventies as a plastic frame you stand on the table.
In 1988 two researchers, independently, solved it: on a seven-by-six grid, with perfect play on both sides, the first player wins — and only by opening in the middle column. Any other first move hands over the draw, or the game. It is one of the few board games whose ending is actually known.
How to play
| Drop a disc | Click or tap a column. It falls to the lowest empty slot. |
|---|---|
| Winning | Four of yours in a row: across, down, or either diagonal. |
| Drawing | Forty-two discs, board full, nobody has four. |
The thing that catches beginners out is that you do not only choose where your disc goes — you also choose what you put under your opponent’s next one. Blocking a threat often means handing over the square directly above it.
Our version
Three strengths of opponent. The weakest one blunders like a person; the strongest one knows about the middle column.
Three things that help
Take the centre column. It is part of more winning lines than any other column, and the solution to the whole game turns on it.
Count the odd and even rows. Against a good opponent, threats on odd rows and threats on even rows are not worth the same, because of who is forced to fill the square beneath.
Build two threats, not one. A single three-in-a-row gets blocked. Two that complete on different columns cannot both be blocked, and that is how nearly every real game is actually won.