adjacency
Adjacency in board games is the relation between spaces or pieces that count as neighbors under the game’s movement or interaction rules [@britannica2026go; @britannica2026halma].
Adjacency matters because the board does not merely store pieces. It structures what those pieces can do next. Attack ranges, legal movement, support effects, enclosure, and blocking all depend on which positions the rules treat as next to each other. In weiqi, neighboring intersections determine liberties and connection. In halma, nearby pieces create the jumps that drive longer transfers across the board [@britannica2026go; @britannica2026halma].