Connect Four strategy: how to win every game you should

Why the centre column is worth more

Connect Four has 69 possible lines of four on a 7×6 board, and they are not spread evenly. The centre column takes part in far more of them than the edges — which is why every piece of good advice about this game starts in the middle.

Three principles follow immediately, and they cover most games:

1. Take the centre. First move, and keep contesting it.
2. Never play under an opponent's winning square.
3. Win by creating two threats at once, because a single move can only block one.

Level 1 — Basic: the four habits

1. Open in the centre, and keep playing centrally

Column 4 first. If your opponent takes it, take column 3 or 5 and fight for the centre from there.

2. Check every diagonal, every move

Before you drop, scan both diagonals through the square you are about to fill and both through the square above it. Almost every unexpected loss in casual play is a diagonal.

3. Never give them a free stack

If your opponent has three in a row with a gap that they cannot yet reach, do not fill the space below it. Play somewhere else — even a move that achieves nothing is better than one that hands over the game.

4. Build a double threat

Two ways to make one:

• Side by side — a three in a row open at both ends.
• Stacked — two winning squares in the same column, one above the other. Your opponent blocks the lower one, and you win on top of it.

Level 2 — Intermediate: odd and even threats

This is the idea that separates players who win sometimes from players who win consistently, and it is the human version of the theory that solved the game.

The parity rule

There are 42 squares. Red plays moves 1, 3, 5… and Yellow plays 2, 4, 6… If the board fills completely, Red takes the odd-numbered squares in each column and Yellow the even ones. That means:

• Red wants threats on odd rows (rows 1, 3 and 5, counting from the bottom).
• Yellow wants threats on even rows (rows 2, 4 and 6).

How to use it

A threat that your opponent can never safely fill acts as a time bomb. As the board fills, someone eventually has to play the column containing it — and because of parity, that someone is predictable. So:

• As Red, create a single threat on an odd row and then simply avoid losing elsewhere. You will win when the board runs out of safe moves.
• As Yellow, do the same on an even row — and try to neutralise Red's odd threat by forcing Red to use up the column first.

Zugzwang: running out of safe moves

Connect Four endgames are pure zugzwang. Nobody wants to move, because every column is either dangerous or gives something away. Count how many "spare" safe moves you have compared with your opponent — the player who runs out first loses.

Level 3 — Advanced: the solved openings and how engines think

Know the opening result

Perfect play is documented. Opening in the centre wins; opening beside it loses; the rest draw. Practically, this means:

• As Red, always play column 4 first, and know that from there a correct game is a forced win — though the win runs almost to the last move.
• As Yellow, your job is to get to a drawn structure quickly: contest the centre, keep parity on your side, and avoid giving Red a second threat.

Allis's control rules, in human terms

The formal solution proves a player can guarantee control of certain squares. Two of those ideas translate directly into usable technique:

• Claimeven. The second player automatically takes the even squares of any column that fills naturally. So a Yellow threat on an even square, in a column nobody wants to touch, is a guaranteed win.
• Baseinverse. Two directly playable squares can never both be taken by the same player, so a threat that needs both is worthless. Check that your "double threat" is really double.

The engine's view

A Connect Four engine is an alpha-beta search with a transposition table, deepening until it runs out of time. Two consequences for a human opponent:

• It never misses a tactical shot, so do not play speculative traps — they lose material you cannot afford.
• Its endgame is perfect. Once the position is small enough, it has solved the game. The only place to beat a strong engine is the early middlegame, by reaching structures where parity favours you.

Practical advanced play

1. Take the centre and build height there — central stacks generate diagonals in both directions.
2. Plant one threat on your own parity, as early as it is safe to do so.
3. Then play the waiting game: avoid creating new weaknesses and let the board fill.
4. Count safe moves constantly. Winning a Connect Four endgame is an exercise in counting, not in searching.

The five mistakes that decide games

1. Playing the edges early. They take part in the fewest fours.
2. Filling the square under a threat because it seemed safe locally.
3. Missing diagonals. Check them before every move, both directions.
4. Blocking one threat and creating another. Look at the square above the one you fill.
5. Ignoring parity. A threat on the wrong row is often worth nothing at all.

Common questions