Wanzhou万州麻将

The tiles: 108 total

Three suits numbered 1–9, four copies each. No winds, no dragons, no flowers: the honor tiles are left in the box entirely, which is why a hand here is all runs, triplets and pairs of numbers.

108 tiles make 54 stacks, which will not divide evenly between four walls. The dealer's wall and the one facing it run 14 stacks; the other two run 13.

换三张: the opening swap

Before anybody discards, every player passes three tiles to a neighbour. It happens once, at the start of each hand, and it is what the ruleset is named after.

1. Each player picks three tiles of a single suit from their hand. The values need not relate: three unconnected dots are as legal as a run. Only the suit has to match.
2. Once all four have committed, the dealer rolls one die to settle which way the tiles travel.
3. All four exchanges happen at the same instant. Three tiles leave as three arrive, so nobody's count ever changes.

• 1 or 4: everyone passes to the player on their right.
• 2 or 5: everyone passes across the table.
• 3 or 6: everyone passes to the player on their left.

Calling a discard

• Chow: never. A run can never be claimed off a discard. Runs still count in a finished hand; you simply have to draw them yourself.
• Pong and kong: allowed, from any player at the table.

When a discard can finish your hand

This is the rule that shapes the whole game. A plain hand (平胡) (four melds and a pair, nothing more) cannot be completed on someone else's discard. You must draw the tile yourself, or rob it out of a kong.

Any better hand can be taken off a discard, at any point in the hand. So the question is never just “am I one tile away”; it is “is my hand worth more than a plain one?”

前四 / 后四: the two windows

At both ends of the wall the restriction lifts and any hand, plain included, may be won off a discard.

• 前四 (Front Four): while fewer than four tiles have been discarded all hand. It closes on the fourth discard and does not come back.
• 后四 (Back Four): once the wall is down to its last four tiles.

During the front window a player who is one tile away may announce ready (报听). Announcing is binding: from then on they are held to the wait they announced, so they may no longer pong or reshape. They may still kong, but only if it leaves the wait exactly where it was, and konging while announced scores a bonus.

Hand types

• 平胡 Plain hand: four melds and a pair. Self-draw only, outside the windows.
• 大对子 All triplets: every set a triplet, no runs.
• 清一色 Full flush: the whole hand in one suit.
• 七对 Seven pairs: fourteen tiles in seven pairs, entirely concealed.
• 龙七对 / 双龙七对 / 三龙七对: seven pairs including one, two or three sets of four, each counting as a “dragon” pair.
• 杠上花: winning on the replacement tile drawn after your own kong.
• 杠上炮: winning on the discard thrown by a player who had just konged.
• 抢杠: robbing the kong, below.
• 单钓将: everything melded, waiting on the pair alone.

Every type above except 平胡 may be completed on a discard whenever it appears.

Seven pairs (七对)

Seven pairs is never four melds and a pair; it is its own shape, and it must be entirely concealed. Konging a set of four you were holding as a pair therefore throws the hand away rather than improving it.

Kongs and robbing the kong (抢杠)

Kongs pay out the moment they are declared and draw a replacement from the dead end of the wall. A kong that puts a tile on show can be robbed: if that tile completes your hand you take it and win instead, and the kong never forms. Robbing works even for a plain hand: it is the one way a plain hand ends on a tile it did not draw. A concealed kong is assembled out of sight and cannot be robbed.