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Frosted Board

Puzzle #20: Four in a Row

  • DifficultyMedium
  • To moveDark
  • TaskWin in 3
  • Main line5 half-moves

Dark to move after 18 discs, with 0 columns already full.

Connect four within 3 of your own moves. Exactly one column starts the win; any other lets the opponent off.

What the position is about

  • forcing sequence — The solution is a series of threats, each one leaving the defence a single answer.
  • horizontal four — The four that wins lies flat, along one row.

Finding the way in

Three-move wins usually start with a forcing move: a threat the opponent has to block, after which your next disc makes a double threat.

Before you touch a piece, list every forcing move you have and every threat the opponent has; the answer is almost always on that short list.

Show the first move

Start with a4. Played out against the stiffest resistance, the whole line goes: a4 a5 b1 d4 b2.

Solve it and the next puzzle of the same game is one tap away. Your solved puzzles are ticked in the list, in this browser only.