Explanation
Open the explanation (shows the answer)
The answer is f8. With best play to the end: +4 (a win by 4).
Best line: f8 g2 h1 g8 h8 pass h5 pass h7 f6
Other moves
| Move | Result | Why |
|---|---|---|
| e7 | -20 (a loss by 20) | Opponent's moves: 5 after this move, 2 after f8. The opponent's best answer is f8 (then h5 f7 f6). |
| g2 | -24 (a loss by 24) | g2 is an X-square (diagonal to the corner h1). While the corner is empty it tends to give the corner away. After this move the opponent can play the corner h1. g2 is in an even region (2 empties); f8 is in an odd one (11). The opponent's best answer is h1 (then h5 h7 e7). |
| h7 | -28 (a loss by 28) | The opponent's best answer is f6 (then c7 c8 h8). |
| f6 | -34 (a loss by 34) | Opponent's moves: 4 after this move, 2 after f8. The opponent's best answer is h5 (then g2 e7 f7). |
| c8 | -36 (a loss by 36) | Opponent's moves: 7 after this move, 2 after f8. Openness: 7 for this move (flips 4), 5 for f8 (flips 1). The opponent's best answer is h5 (then g2 h1 f6). |
| g8 | -38 (a loss by 38) | The opponent's best answer is h5 (then g2 h1 e7). |
| c7 | -42 (a loss by 42) | Opponent's moves: 5 after this move, 2 after f8. The opponent's best answer is c8 (then h5 f6 h7). |
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.