How to win Connect Four: strategy that beats most players

01Why Connect Four rewards planning

Connect Four is a perfect-information game: there are no dice and no hidden cards, so every result comes from decisions you can see on the board. The grid is only seven columns by six rows, yet a position can be won or lost many moves before it looks that way. That is why a patient player beats an impatient one so reliably.

The game has even been solved. With perfect play the first player wins by starting in the centre column. You do not need to play perfectly to benefit from that fact. It tells you where the strength of the board lies, and the rest of this guide turns that into habits you can use in a real game, whether you are playing a friend or the computer in our Connect Four.

021. Start in the centre column

There are 69 possible lines of four on the board. The middle column, the fourth of seven, is part of more of them than any other column, and a disc there can join rows, columns and both diagonals. A disc in an outer column can only be part of a few lines.

If you move first, open in the centre. If you move second and your opponent opens off-centre, take the centre yourself. If they open in the centre, reply right beside it in the third or fifth column, and keep fighting for the centre column's higher squares as the game goes on. Whoever owns the middle of the board usually has more choices at every turn.

032. Check for threats before every move

Before you drop a disc, ask the same two questions every single time. Can I win with my next disc? Can my opponent win with theirs? If the answer to the first is yes, take the win. If the answer to the second is yes, block it, unless you can win first. Most games between casual players end because one of them skipped this check.

Scan in all four directions: across the row, up the column, and along both diagonals. The diagonals are the ones people miss, especially a diagonal that only becomes visible after a disc lands in a neighbouring column.

043. Never play under your opponent's winning square

A winning square is an empty space that would complete four for one player. If your opponent has a winning square in a column, the space directly below it is poisoned for you: if you drop there, they drop on top and win. Pay attention to this when you are tempted by a square that looks harmless.

The reverse is a weapon. If you have a winning square in a column, your opponent must never play below it, and neither should you unless you have to. As the board fills up, the other player may run out of safe moves and be forced to play underneath your threat. That is how many games are won without any dramatic tactic.

054. Build an open three on the bottom row

An open three is three of your discs in a row with an empty, playable space at both ends. On the bottom row every space is playable, so three discs in the middle of the row, with both ends empty, make two winning squares at once. Your opponent can only block one, and you play the other.

Say you have discs in the third, fourth and fifth columns of the bottom row, and the second and sixth columns are empty. You threaten to win in either of them. A careful opponent stops you before this happens, by putting a disc on one of the ends as soon as you have two in the middle. So the real skill is making the pattern while giving the other player something else to worry about.

065. Stack two threats in one column

Two winning squares directly on top of each other in the same column are deadly. Suppose you can complete four at the third square of a column and also at the fourth. Your opponent cannot play the third square, because that lets you take the fourth, and if they leave it alone you can play it yourself and win. Either way you win.

You build a stacked threat by creating one winning square, and then working on a second line that passes through the square directly above it. It takes patience, but it wins games against opponents who only look at one threat at a time.

076. Learn odd and even threats

Number the rows from the bottom, one to six. Because the two players alternate and 42 spaces are shared between them, a quiet endgame tends to be decided by parity. As a rule of thumb, the player who moves first, usually Red, benefits from a winning square on an odd row (first, third or fifth), and the player who moves second benefits from a winning square on an even row (second, fourth or sixth).

The reason is simple. When all the other columns are full, the remaining squares fill in order, and the first player ends up dropping into odd rows while the second player drops into even rows. A threat on your own parity is hard for the opponent to avoid, because they will eventually be the one forced to play underneath it. If you are first player, hunt for threats on rows three and five. If you are second player, aim for rows two, four and six, and be happy to trade off the rest.

087. Do not forget the diagonals

Rows and columns are easy to read. Diagonals need the lower discs to be in place first, which makes them slow to build and easy to overlook. Because the board fills from the bottom, a diagonal often needs a disc that will not exist for several turns. Good players plan which disc will support their diagonal and which columns the opponent will be forced to fill.

Play your discs so they serve two jobs at once: part of a row now, part of a diagonal later. A disc that helps in only one direction is worth far less than one that works in two.

098. Control the tempo

Sometimes the best move is a quiet one. If every move you can see weakens your position, look for a waiting move: a disc in a column that changes nothing important. Count the safe moves left for each side. If you have more safe waiting moves than your opponent, they will run out first and be forced to play underneath a threat.

This is the heart of the endgame. A single safe column with a few spaces left can be worth more than a flashy attack that burns your useful discs.

10How to beat each computer level

Against Easy, play the centre and make any open three. It will often fail to block. Against Medium, you need a double threat: it blocks single threats reliably but looks only a few moves ahead, so a stacked threat or a bottom-row open three created with a tempo will beat it.

Hard is a different animal. It runs a deep alpha-beta search and solves the late game exactly, so tricks do not work. The way to beat it is to reach a position where parity is on your side before the board starts to fill, and then play quietly. Switch on hints to see how the computer rates each column, and replay games where you lost to find the move where the evaluation changed.

11The mistakes that lose most games

These are the most common errors in casual games, roughly from the most costly down.

• Playing an outer column early because it looks safe. It gives the centre away.
• Forgetting a diagonal threat and losing to a disc that landed beside it.
• Dropping a disc under an opponent's winning square.
• Blocking a single threat with a move that creates a bigger one for the opponent.
• Making three in a row on the side of the board where both ends are already blocked.
• Hurrying. Every strong player pauses before the move that fills the third row.

12A short practice routine

Play three games against Medium with hints on, and read what the hints say each time they disagree with you. Then play three games on Hard with hints off and take notes on the move where you realised you were worse. Finally, play a friend on one screen and try to win using only a stacked threat. Within a week you will see threats you used to miss.

When you are ready for a real opponent, send a friend a link from the online mode. It takes about twenty seconds, and a human who also knows the centre rule is a much better teacher than a computer.

13Play Connect Four now

Everything above is easier to learn on a board than from a page. Open Connect Four and play against the computer on any level, with a friend on the same screen, or online. It is free and needs no sign-up. If you enjoy short two-player strategy games, our Tic Tac Toe has bigger boards too.