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Learn Connect Four

Gravity, four in a row, and the centre column.

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Pick a column

You choose the column. The disc falls as far as it can.

Tap any column to drop a red disc.

The story

A Game With Many Names

Connect Four has been sold under many names since the nineteenth century. The 1974 Milton Bradley version fixed the seven-by-six board and the standing frame that makes the discs fall.

The whole story

Connect Four reached most people through the plastic yellow frame Milton Bradley sold from 1974, but the idea is older and has been sold under a dozen names — Captain's Mistress, Four in a Row, Plot Four, Gravitrips. The Captain's Mistress name attaches to a story, probably invented, that Captain James Cook spent so many hours at a four-in-a-row game in his cabin that his crew grew suspicious of what was keeping him there. What the 1974 version fixed was the shape: seven columns, six rows, and the vertical frame that makes the discs fall.

Solved, Twice, in 1988

Connect Four was solved in 1988. The first player wins with perfect play, but only by opening in the centre column. Every other opening is a draw.

The whole story

Connect Four is a solved game: with perfect play from both sides the first player wins. James Allen and Victor Allis proved it independently in October 1988, within days of each other and by different methods — Allen by exhaustive search, Allis by building a knowledge-based system from nine strategic rules. The winning first move is the centre column, and it is the only winning first move. Play any of the other six and the game is a draw with perfect play; play the two outermost columns badly and you can lose outright.

The full notes

Everything above, and more, in words, to read or to listen to.

Rules2 sections

How a Move Works

You choose a column, not a square. The disc falls to the lowest empty cell in that column, and where it comes to rest is not up to you — that is the whole character of the game. Red plays first, then the players alternate. The aim is four of your discs in an unbroken line: across a row, up a column, or along either diagonal. The first player to make one wins immediately. A column that is full cannot be played into, and if every column fills with nobody having made four, the game is a draw.

  • You control the column; gravity controls the row.
  • Diagonals count in both directions, and they are the lines people miss.

Why It Always Ends

Connect Four cannot go on forever, and this is worth noticing because most board games need a rule to guarantee it. Chess has the fifty-move rule; checkers needs something similar. Connect Four needs nothing: every move fills a cell, no cell is ever emptied, and there are only forty-two of them. Whatever either player does, the game is over within forty-two moves. There are no repeated positions to detect, because a position can never repeat.

  • A position can never repeat, so there is no draw-by-repetition rule.
  • Forty-two moves is the hard ceiling on a standard board.
Strategy3 sections

Take the Middle

The centre column is on more four-in-a-row lines than any other — every horizontal line through the middle, the long diagonals, and its own column. A disc there is doing more work than the same disc on the edge, and the edge columns are on the fewest lines of all. This is why the solved opening is the centre, and it is also the most useful single habit for a beginner: when nothing obvious is happening, play towards the middle.

  • Count the lines through a cell to see why the centre is worth more.
  • Discs on the outer columns are the least useful ones you own.

The Double Threat

Blocking works exactly once per turn. So the way games are actually won is by making two threats at the same time: a position where you have two different cells that would each complete a four. Your opponent blocks one, you play the other. Almost every Connect Four loss between competent players is this — not a four that was missed, but a fork that was allowed. An open three, with a playable cell at both ends, is the standard shape.

  • One threat is blocked. Two at once cannot be.
  • Watch for shapes that will become a double threat once a cell beneath them is filled.

Never Fill the Cell Beneath a Threat

Gravity means a threat only matters once the cell beneath it is occupied. This cuts both ways and is where most beginners lose games without understanding why. If your opponent has a winning cell one row up, playing directly beneath it hands them the win — you build their staircase. Strong players count parity for exactly this reason: on a standard board the columns have an even height, so whose turn it is when a column reaches a critical row is often decided many moves earlier.

  • Before playing a column, look at the cell your disc would open up.
  • The threat you can safely ignore is the one nothing can reach yet.