Robbing the Kong

Robbing the Kong (chankan in Japanese Riichi, qiang gang hu in Chinese) is a special way to win by claiming the very tile an opponent is using to upgrade an existing open pung (triplet) into a kong. When a player already has an exposed pung on the table and then draws the fourth matching tile, they may 'add' it to promote the pung to a kong; if that added tile happens to be the exact tile another player needs to complete their winning hand, that player can interrupt and take it as their winning tile instead of letting the kong form.

In Riichi, chankan is a 1-han yaku and can be declared on a closed hand, making it one of the rarer yaku to actually appear. The robbed player does not get their kong; the win supersedes the kong declaration, and the robber is treated as winning by ron off that player. A crucial restriction in most rules is that robbing applies only to the added (shouminkan) upgrade of an open pung — you generally cannot rob a fully concealed kong, with the famous exception that thirteen orphans may rob even a concealed kong in some rulesets.

For a concrete case: you are waiting on 5p to complete a sequence, and an opponent who already has an exposed pung of 5p draws the fourth 5p and announces adding it to make a kong — you call chankan and win on that 5p. In Hong Kong and Chinese rules the same robbing-the-kong win exists and typically grants a bonus faan or fan. A common confusion is thinking you can rob any kong; only the promotion of an already-melded pung is fair game under standard rules, which is what makes the situation uncommon.