Explanation
Open the explanation (shows the answer)
The answer is b5. With best play to the end: +2 (a win by 2).
Best line: b5 f2 e2 f1 h1 h3 h5 h4 b2 h7
Other moves
| Move | Result | Why |
|---|---|---|
| f2 | -4 (a loss by 4) | The opponent's best answer is b5 (then h1 h5 h2). |
| h1 | -8 (a loss by 8) | Opponent's moves: 6 after this move, 4 after b5. Openness: 6 for this move (flips 3), 0 for b5 (flips 3). The opponent's best answer is b5 (then h5 f2 h2). |
| h4 | -10 (a loss by 10) | Opponent's moves: 6 after this move, 4 after b5. Openness: 2 for this move (flips 1), 0 for b5 (flips 3). The opponent's best answer is b5 (then e2 f1 h1). |
| h2 | -12 (a loss by 12) | Opponent's moves: 6 after this move, 4 after b5. Openness: 3 for this move (flips 1), 0 for b5 (flips 3). The opponent's best answer is h3 (then b5 h1 f2). |
| b2 | -18 (a loss by 18) | The opponent's best answer is b5 (then f2 e2 h1). |
| h3 | -22 (a loss by 22) | Opponent's moves: 7 after this move, 4 after b5. Openness: 5 for this move (flips 3), 0 for b5 (flips 3). The opponent's best answer is b5 (then b2 h5 h4). |
| g1 | -26 (a loss by 26) | g1 is a C-square (next to the corner h1). In this shape it lets the corner be taken. Opponent's moves: 9 after this move, 4 after b5. Openness: 7 for this move (flips 3), 0 for b5 (flips 3). The opponent's best answer is h1 (then e2 f1 b5). |
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.