Explanation
Open the explanation (shows the answer)
The answer is g7. With best play to the end: +12 (a win by 12).
Best line: g7 a6 a7 b7 d8 c8 a8 b8 f8 g8
Other moves
| Move | Result | Why |
|---|---|---|
| b8 | -2 (a loss by 2) | Openness: 3 for this move (flips 1), 0 for g7 (flips 2). The opponent's best answer is g7 (then d8 c8 b7). |
| b7 | -4 (a loss by 4) | 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. Opponent's moves: 5 after this move, 3 after g7. The opponent's best answer is g7 (then b8 c8 g8). |
| c8 | -6 (a loss by 6) | Opponent's moves: 5 after this move, 3 after g7. Openness: 3 for this move (flips 4), 0 for g7 (flips 2). The opponent's best answer is g7 (then f8 g8 pass). |
| d8 | -6 (a loss by 6) | Opponent's moves: 5 after this move, 3 after g7. Openness: 4 for this move (flips 3), 0 for g7 (flips 2). The opponent's best answer is g7 (then b7 a6 f8). |
| f8 | -8 (a loss by 8) | Opponent's moves: 5 after this move, 3 after g7. Openness: 3 for this move (flips 2), 0 for g7 (flips 2). The opponent's best answer is g8 (then g7 d8 c8). |
| g8 | -10 (a loss by 10) | Openness: 2 for this move (flips 2), 0 for g7 (flips 2). The opponent's best answer is g7 (then f8 d8 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.