Explanation
Open the explanation (shows the answer)
The answer is c1. With best play to the end: +12 (a win by 12).
Best line: c1 a1 a2 a7 b7 b8 a8 pass h1 h2
Other moves
| Move | Result | Why |
|---|---|---|
| h1 | -12 (a loss by 12) | h1 is in an even region (2 empties); c1 is in an odd one (1). Opponent's moves: 5 after this move, 3 after c1. Openness: 2 for this move (flips 1), 0 for c1 (flips 4). The opponent's best answer is a1 (then a2 c1 b7). |
| g7 | -24 (a loss by 24) | g7 is an X-square (diagonal to the corner h8). While the corner is empty it tends to give the corner away. g7 is in an even region (2 empties); c1 is in an odd one (1). The opponent's best answer is c1 (then h1 h8 b7). |
| b7 | -24 (a loss by 24) | b7 is an X-square (diagonal to the corner a8). While the corner is empty it tends to give the corner away. After this move the opponent can play the corner a8. b7 is in an even region (4 empties); c1 is in an odd one (1). The opponent's best answer is c1 (then f1 a1 a2). |
| f1 | -36 (a loss by 36) | After this move the opponent can play the corner h1. Opponent's moves: 6 after this move, 3 after c1. Openness: 2 for this move (flips 5), 0 for c1 (flips 4). The opponent's best answer is c1 (then g7 a1 h2). |
| h2 | -48 (a loss by 48) | h2 is a C-square (next to the corner h1). In this shape it lets the corner be taken. h2 is in an even region (2 empties); c1 is in an odd one (1). Opponent's moves: 6 after this move, 3 after c1. The opponent's best answer is f1 (then b7 c1 b8). |
About these puzzles
Each position comes from a real game. The engine solved it to the end (perfect play by both sides) and only positions with a single best move, clearly better than the second-best move, were kept. "Best play wins by N" is the final disc margin when both sides play perfectly.
If you play a different move, you see the final margin your move leads to with perfect play afterwards, and how much it gave up. Results are stored only in this browser.
To be graded during a full game, go to the Reversi dojo.