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Frosted Board

Puzzle #30: Dots and Boxes

  • DifficultyHard
  • To moveLight
  • TaskTake 14 of 25
  • Main line31 half-moves

Light to move on the 5 × 5 board. 29 of 60 lines are drawn, Dark has 0 boxes and Light 0.

25 boxes are still unclaimed. With best play you can take 14 of them, 3 more than the opponent gets, and exactly one line achieves that.

What the position is about

  • sacrifice — A piece is given up on purpose: the forced capture pulls the opponent onto the square you need.
  • keep control — With best play you stay in control and collect more than half of what is left.

Finding the way in

On 5×5 the chains are long and the loops expensive. Work out the value of opening each component, and open the cheapest one for the opponent to take.

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 b1-b2. Played out against the stiffest resistance, the whole line goes: b1-b2 b2-c2 a1-a2 c1-d1 d1-d2 d2-e2 d2-d3 c2-c3 b2-b3 a3-b3 b3-b4 e2-f2 f1-f2 f2-f3 e4-f4 f3-f4 f4-f5 a5-b5 a4-a5 b6-c6 b5-b6 b4-c4 c3-c4 d3-d4 d4-e4 c4-c5 d4-d5 c6-d6 d5-d6 e5-e6 e6-f6.

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.