How to win at four in a row (it's a solved game, and that helps you)

Four in a row is one of the very few games that has been solved — not "figured out", solved, in the mathematical sense. In 1988 two people independently proved that on the standard seven-by-six board, the player who moves first can always win with perfect play, and that the winning first move is the centre column.

That sounds like it ruins the game. It doesn't, because nobody plays perfectly. What it does is tell you exactly where the advantage lives, which is more useful than any amount of intuition.

Why the centre column

Count the lines.

Any four-in-a-row has to run horizontally, vertically, or on one of the two diagonals. Now ask how many of those possible lines pass through each column. A disc in the outermost column can only ever be part of lines that run inward — it has neighbours on one side only. A disc in the centre column participates in horizontal lines starting from four different positions, vertical lines, and both diagonal directions.

On a seven-wide board the centre column takes part in substantially more possible winning lines than any other. Every disc you put there is worth more than the same disc anywhere else, both as an attack and as a block.

The practical version: open in the middle, and don't give the middle away for something that looks clever. A flashy edge play that concedes the centre is how a game gets lost four moves before anyone notices.

The double threat is how games actually end

Blocking one threat is trivial. You see three of your opponent's discs in a line with an open end, you fill the end, nothing happened.

Games are won by building a position with two open ends at once, because your opponent only gets one move. They block one, you play the other.

Setting one up means thinking a move earlier than the threat itself. The move that wins the game is usually not the move that creates a threat — it's the quiet one before it, that makes two threats possible next turn.

Which is also the tell going the other way. If your opponent makes a move in the middle of the board that doesn't seem to do anything, don't relax. Count the lines it just opened.

The thing nobody tells beginners: you're playing two boards

Because discs fall to the bottom of a column, every move you make hands your opponent the square directly above it.

That's the real strategic content of the game and it's completely invisible at first. You can't play a square; you can only play a column, and the board decides where your disc lands. So a move that's good for you often builds a platform for them.

This is why experienced players sometimes refuse to play into a column that looks appealing. They're not being clever, they're avoiding handing over the winning slot.

The habit: before you drop a disc, look at the square above it and ask whether your opponent wants that square. If they do, you're not making a move, you're making them a present.

Parity, briefly, because it decides close games

Here's the version that's actually usable without doing arithmetic mid-game.

The board has six rows. Every column fills from the bottom, so the squares in any column alternate between "reachable on an odd-numbered move" and "reachable on an even-numbered move". Because the first player takes odd moves and the second player takes even ones, each player naturally tends to land on alternating rows.

The consequence you can actually use: if you're the first player, threats you build on odd rows (counting from the bottom) are the ones you're more likely to be able to complete. If you're second, even rows are yours. When you have a choice between two ways to build the same threat, build it on your own parity.

You don't need to track this precisely. Just knowing it exists explains the otherwise baffling experience of building a beautiful threat and finding you can never actually reach the winning square.

A checklist that will beat most people

1. Open in the centre. Every time. It's the strongest square and everything else is a concession.
2. Before each move, check for their three-in-a-row. Boring, and the single most common way games are thrown away.
3. Then check for yours. In that order — an unnoticed threat against you costs more than a missed win.
4. Look above the square you're about to fill. If they want it, play elsewhere.
5. Build toward two threats, not one. One threat is a move. Two is a win.
6. Watch their quiet moves. The dangerous one never looks dangerous.

Why this game survives a slow opponent

Four in a row is one of the few genuinely good games to play a move a day. The position is small enough to reload instantly — you glance at the board and you're back where you were, with no memory of a plan required, because the plan is visible in the discs.

Chess doesn't have that property. Neither do most card games. A four-in-a-row board is fully legible in about two seconds, which makes it the right size for a game that runs across a week of one move each per day.