Explanation
Open the explanation (shows the answer)
The answer is b5. With best play to the end: +4 (a win by 4).
Best line: b5 b6 a7 a2 h8 a5 b3 a6 a1 b2
Other moves
| Move | Result | Why |
|---|---|---|
| a5 | -2 (a loss by 2) | The opponent's best answer is b6 (then b5 a6 a7). |
| b3 | -18 (a loss by 18) | The opponent's best answer is a5 (then b5 a6 b6). |
| a6 | -26 (a loss by 26) | The opponent's best answer is b5 (then b6 a7 a5). |
| b6 | -32 (a loss by 32) | Openness: 3 for this move (flips 3), 1 for b5 (flips 2). The opponent's best answer is a2 (then b3 b2 b1). |
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.