Explanation
Open the explanation (shows the answer)
The answer is b2. With best play to the end: +4 (a win by 4).
Best line: b2 g2 b7 g1 h1 f1 h2 h7 h8 a8
Other moves
| Move | Result | Why |
|---|---|---|
| b7 | -12 (a loss by 12) | b7 is an X-square (diagonal to the corner a8). While the corner is empty it tends to give the corner away. The opponent's best answer is a2 (then a3 b2 b8). |
| b8 | -22 (a loss by 22) | b8 is a C-square (next to the corner a8). In this shape it lets the corner be taken. Opponent's moves: 10 after this move, 8 after b2. The opponent's best answer is a8 (then b2 a3 a2). |
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.