Explanation
Open the explanation (shows the answer)
The answer is g7. With best play to the end: +10 (a win by 10).
Best line: g7 b8 g2 g1 c2 c1 b2 b1 a1 pass
Other moves
| Move | Result | Why |
|---|---|---|
| b2 | -2 (a loss by 2) | b2 is an X-square (diagonal to the corner a1). While the corner is empty it tends to give the corner away. After this move the opponent can play the corner a1. Opponent's moves: 7 after this move, 4 after g7. The opponent's best answer is g7 (then c1 c2 e1). |
| c1 | -2 (a loss by 2) | Opponent's moves: 8 after this move, 4 after g7. Openness: 2 for this move (flips 1), 0 for g7 (flips 3). The opponent's best answer is g7 (then b2 c2 e1). |
| g1 | -4 (a loss by 4) | g1 is a C-square (next to the corner h1). In this shape it lets the corner be taken. g1 is in an even region (4 empties); g7 is in an odd one (1). Opponent's moves: 6 after this move, 4 after g7. The opponent's best answer is g7 (then g2 b8 b2). |
| g2 | -4 (a loss by 4) | 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. g2 is in an even region (4 empties); g7 is in an odd one (1). The opponent's best answer is g7 (then g1 b8 b2). |
| c2 | -10 (a loss by 10) | Opponent's moves: 6 after this move, 4 after g7. The opponent's best answer is g7 (then c1 b8 g1). |
| e1 | -10 (a loss by 10) | Opponent's moves: 7 after this move, 4 after g7. Openness: 5 for this move (flips 4), 0 for g7 (flips 3). The opponent's best answer is g7 (then c1 b1 c2). |
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.