碁
ゴ
Go
JLPT1 G7 S13 F1609
As per
其
# (square/rectangular) +
石
stone → game in which stone pieces are used on a rectangular board/table → (the game of) *go*. Unlike
棋
, which can refer to both go and shogi,
碁
refers only to go.
[Full Kanji Etymology List]