Explanation
Open the explanation (shows the answer)
The answer is a2. With best play to the end: +6 (a win by 6).
Best line: a2 a4 g1 d8 f6 g2 f7 f8 h1 h8
Other moves
| Move | Result | Why |
|---|---|---|
| g2 | -12 (a loss by 12) | 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. Opponent's moves: 7 after this move, 5 after a2. The opponent's best answer is f6 (then a2 h1 g1). |
| f6 | -12 (a loss by 12) | After this move the opponent can play the corner h8. Opponent's moves: 7 after this move, 5 after a2. The opponent's best answer is h8 (then g1 a4 a2). |
| d7 | -14 (a loss by 14) | Opponent's moves: 7 after this move, 5 after a2. Openness: 2 for this move (flips 4), 0 for a2 (flips 2). The opponent's best answer is f6 (then g1 a4 a2). |
| f8 | -14 (a loss by 14) | Opponent's moves: 7 after this move, 5 after a2. Openness: 6 for this move (flips 4), 0 for a2 (flips 2). The opponent's best answer is f6 (then a2 a4 g2). |
| e8 | -14 (a loss by 14) | Opponent's moves: 8 after this move, 5 after a2. Openness: 5 for this move (flips 2), 0 for a2 (flips 2). The opponent's best answer is f6 (then g1 a4 a2). |
| g1 | -20 (a loss by 20) | Openness: 2 for this move (flips 7), 0 for a2 (flips 2). The opponent's best answer is f6 (then d7 a4 a2). |
| a4 | -22 (a loss by 22) | The opponent's best answer is a2 (then g2 d8 g1). |
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.