Explanation
Open the explanation (shows the answer)
The answer is e8. With best play to the end: +4 (a win by 4).
Best line: e8 h4 g8 b8 h7 c8 h5 h8 g7 pass
Other moves
| Move | Result | Why |
|---|---|---|
| h4 | -6 (a loss by 6) | h4 is in an even region (2 empties); e8 is in an odd one (1). The opponent's best answer is e8 (then c8 a8 g8). |
| a7 | -8 (a loss by 8) | a7 is a C-square (next to the corner a8). In this shape it lets the corner be taken. a7 is in an even region (4 empties); e8 is in an odd one (1). The opponent's best answer is h5 (then h4 a8 b8). |
| h5 | -10 (a loss by 10) | h5 is in an even region (2 empties); e8 is in an odd one (1). The opponent's best answer is h4 (then e8 g7 g8). |
| h7 | -10 (a loss by 10) | h7 is in an even region (4 empties); e8 is in an odd one (1). Opponent's moves: 7 after this move, 5 after e8. Openness: 2 for this move (flips 1), 0 for e8 (flips 2). The opponent's best answer is e8 (then h4 a8 a7). |
| g8 | -10 (a loss by 10) | g8 is a C-square (next to the corner h8). In this shape it lets the corner be taken. g8 is in an even region (4 empties); e8 is in an odd one (1). Opponent's moves: 8 after this move, 5 after e8. The opponent's best answer is e8 (then a7 a8 g7). |
| g7 | -22 (a loss by 22) | g7 is an X-square (diagonal to the corner h8). While the corner is empty it tends to give the corner away. After this move the opponent can play the corner h8. g7 is in an even region (4 empties); e8 is in an odd one (1). The opponent's best answer is h8 (then h4 g8 e8). |
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.