Explanation
Open the explanation (shows the answer)
The answer is a5. With best play to the end: +8 (a win by 8).
Best line: a5 a6 a7 b6 a1 e1 d1 d2 e2 b2
Other moves
| Move | Result | Why |
|---|---|---|
| a6 | -8 (a loss by 8) | The opponent's best answer is b6 (then a7 a5 pass). |
| b6 | -10 (a loss by 10) | The opponent's best answer is a7 (then a5 a6 pass). |
| a7 | -14 (a loss by 14) | The opponent's best answer is b6 (then a6 a5 pass). |
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.