Explanation
Open the explanation (shows the answer)
The answer is e8. With best play to the end: +6 (a win by 6).
Best line: e8 h3 c8 h7 a8 b8 a7 a6 h2 g8
Other moves
| Move | Result | Why |
|---|---|---|
| h2 | -20 (a loss by 20) | h2 is in an even region (2 empties); e8 is in an odd one (1). The opponent's best answer is h3 (then e8 h7 g7). |
| a6 | -26 (a loss by 26) | The opponent's best answer is a7 (then h2 g7 h3). |
| a7 | -34 (a loss by 34) | a7 is a C-square (next to the corner a8). In this shape it lets the corner be taken. Opponent's moves: 8 after this move, 4 after e8. Openness: 5 for this move (flips 4), 0 for e8 (flips 1). The opponent's best answer is h3 (then a6 g7 h2). |
| c8 | -38 (a loss by 38) | Opponent's moves: 6 after this move, 4 after e8. Openness: 2 for this move (flips 4), 0 for e8 (flips 1). The opponent's best answer is e8 (then h2 h3 g7). |
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.