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Connect Four strategy — how to beat anyone and understand the AI

📅 April 2026⏱ 5 min read🏷 Strategy

Connect Four was solved by mathematicians in 1988. The first player always wins with perfect play. But that doesn't mean knowing strategy is pointless — it means the player who knows the strategy wins. Here's what you need to know.

The basics

The board is 6 rows × 7 columns. Discs drop to the lowest available row in a column. First player to connect four discs in a row — horizontally, vertically or diagonally — wins. The game is solved: with perfect play, the first player always wins.

Always start in the center column

Column 4 (the center) is in the most winning lines. Playing there first maximises your options. If you go second, try to mirror moves toward the center. Never start in the outer columns — they lead to easily contained positions.

✅ Opening principle

First player: column 4. Second player: column 4 or column 3/5. Avoid columns 1, 2, 6, 7 in the first two moves — you give up too much central control.

Create double threats (the key to winning)

The winning move in most Connect Four games is creating two threats simultaneously so your opponent can only block one. This is called a "seven" (the shape looks like a 7) or a fork. To set one up:

  1. Build two diagonal threats that share a common cell at different heights.
  2. Force your opponent to fill a column that inadvertently sets up your winning square.
  3. You win when they are forced to give you the cell that completes both threats.

The odd/even rule (advanced)

Empty squares in a column alternate between "odd" (reachable on an odd-numbered move) and "even" (reachable on an even-numbered move). The first player wins threats on odd rows, the second player wins threats on even rows. Use this to plan which threats to build — aim for odd-row threats if you go first, even-row if you go second.

✅ Practical shortcut

As first player, try to ensure your winning square is in an odd row (rows 1, 3, 5 from the bottom). This means your opponent can never safely fill the column that hands you the win.

How the Hard AI beats you

Our Hard AI uses minimax with alpha-beta pruning at depth 4 — it looks 4 moves ahead, evaluates every position, and picks the move that maximises its advantage while assuming you play perfectly. It's beatable by a human who sets up deep double threats that extend beyond its 4-move lookahead.

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Common mistakes to avoid