Four Seas Mahjong Intermediate Edition: Rules Explained

This article supplements Four Seas Mahjong (Intermediate Edition): Entertaining Hand-Building Rules, with reference to Four Seas Mahjong (Basic Edition): Recreational Hand-Building Rules and Four Seas Mahjong Basic Edition: Rules Explained.

1. Pattern selection

1. All Types may combine with the basic winning structure or Seven Pairs, but not All Unrelated or Thirteen Orphans.

2. All Terminals and Honors cannot combine with Thirteen Orphans, but may combine with Seven Pairs.

3. The rules adopt All Linked, also called Every Set Contains One Rank or Mantingfang. To support hand-building, they introduce Mixed Linked, which permits one honor pung or an honor pair. The Linked family cannot combine with Seven Pairs. It can combine with the Outside Hands family because the two belong to separate rank-based categories. For example, a hand may combine Mixed Outside Hand with Mixed Linked on rank one:

Or Pure Outside Hand with All Linked on rank nine:

4. Two Terminal Sequences, Pure Straight, and Golden Bridge are same-suit chow combinations symmetric across ranks one through nine. The Advanced Edition's Pure Terminal Sequences is a still higher pattern. These form the same-suit symmetry family, or straight family. The Chinese name for Golden Bridge, formerly 一色四连环, is therefore changed to 连环龙 to emphasize its membership in that family.

Pure Straight is also a higher pattern of Half Straight. Consequently, the same-suit symmetry and same-suit consecutive-chow families cannot combine; they are two subcategories within the straight category.

For the same reason, the Three Similar Sequences, Three Similar Triplets, and mirrored families cannot combine with one another. They are treated as subcategories of the three-suit matching chow–pung category.

5. Blessing of Earth and Blessing of Human are distinguished. The former is a self-drawn win; the latter is won on another player's discard but treated as self-draw for payments. The values of Blessing of Heaven and Blessing of Earth are raised to the near-limit tier.

6. Pattern mnemonics:

“一对幺、五不带” — six whole-hand families: one-suit hands, triplets, outside hands, All Types, unrelated hands, and linked hands.

“三龙般、六花镜” — six chow families: three-suit matching chows, straights, identical chows, half straights, assorted straights, and mirrored patterns.

The Basic Edition's eighteen patterns, shown in red and yellow in the original chart, already introduce the families represented by “一对幺、三龙般” and kongs, dragons, and winds. Of the Intermediate Edition's thirty-one additional patterns, fifteen are lower or higher patterns in existing Basic families; sixteen introduce the new families represented by “五不带、六花镜.”

Four Seas Mahjong Intermediate Edition 3.1

Group	Category / subcategory	Pattern	Points
Suit	—	All Types	20
Suit	—	Mixed One-Suit	30
Suit	—	Pure One-Suit	60
Hand structure	Basic	All Sequences	5
Hand structure	Basic	All Triplets	30
Hand structure	Basic	Seven Pairs	60
Hand structure	Special	Honors and Knitted Tiles	30
Hand structure	Special	Seven Honors and Knitted Tiles	40
Hand structure	Special	Five Honors and Knitted Straight	60
Hand structure	Special	Thirteen Orphans	160
Rank	Terminals and honors	All Simples	5
Rank	Terminals and honors	Mixed Outside Hand	30
Rank	Terminals and honors	Pure Outside Hand	40
Rank	Terminals and honors	All Terminals and Honors	80
Rank	Linked patterns	Mixed Linked	20
Rank	Linked patterns	All Linked	40
Rank	Linked patterns	All Symmetric	80
Pungs and kongs	Kongs	One Quad	10
Pungs and kongs	Kongs	Two Quads	30
Pungs and kongs	Kongs	Three Quads	120
Honors	Dragons	Value Honor	10
Honors	Dragons	Little Three Dragons	80
Honors	Dragons	Big Three Dragons	160
Honors	Winds	Little Three Winds	30
Honors	Winds	Big Three Winds	80
One suit	Matching chows	Two Identical Sequences	10
One suit	Matching chows	Two Identical Sequences Twice	80
One suit	Matching chows	Three Identical Sequences	120
One suit	Shifted chows	Two Shifted Sequences	5
One suit	Shifted chows	Three Shifted Sequences	60
One suit	Shifted chows	Two Shifted Sequences Twice	60
One suit	Shifted chows	Four Shifted Sequences	160
One suit	Straight / symmetry	Two Terminal Sequences	5
One suit	Straight / symmetry	Pure Straight	40
One suit	Straight / symmetry	Golden Bridge	120
One suit	Straight / continuity	Half Straight	5
One suit	Straight / continuity	Half Straight Twice	40
One suit	Straight / continuity	Mirrored Half Straight	60
Three suits	Matching chows	Two Similar Sequences	5
Three suits	Matching chows	Three Similar Sequences	30
Three suits	Matching chows	Mirrored Sequences	40
Three suits	Consecutive chows	Assorted Straight	20
Chance	Turn circumstances	Last Tile Draw	20
Chance	Turn circumstances	Last Tile Claim	20
Chance	Turn circumstances	Blessing of Human	60
Chance	Turn circumstances	Blessing of Earth	120
Chance	Turn circumstances	Blessing of Heaven	160
Chance	Kong circumstances	Robbing a Kong	20
Chance	Kong circumstances	Win On Kong	20

Winning requirement	Self-draw	Discard win
Beginner	10	10
Standard	10	20

Four Seas payment system; hand score H, payment threshold 50

Outcome	Winner	Discarder	Each other player
Self-draw	+6H	—	−2H (all three opponents)
Discard win, H ≤ 50	+4H	−2H	−H
Discard win, H > 50	+4H	−(4H − 100)	−50

2. Pattern classification and scoring

Compared with the Basic Edition, the Intermediate classification adds subcategories. These distinguish families within one category that cannot combine but have somewhat different structural justifications. For example, within the rank group and numerical category, the linked-rank and odd/even families form separate subcategories. Both are defined by numbered-tile ranks: linked patterns require every chow, pung, and pair to contain a particular rank, while odd/even patterns require every tile to be odd or every tile to be even. The two families therefore do not combine.

The principle of no reuse within a category applies to every chow, pung, and pair in a winning hand. Each can be used only once within a category, even across different subcategories. Consider:

After forming Pure Straight, Two Identical Sequences, and All Sequences, the 456 characters cannot also combine with 123 or 789 characters for Half Straight. Half Straight and Pure Straight belong to different subcategories of the same same-suit straight category.

Another interpretation is to treat 123456 characters and 456789 characters as Half Straight Twice, together with Two Identical Sequences. However, Half Straight Twice already includes All Sequences, so this interpretation scores five points less. The higher-scoring first interpretation should be used.

Zung Jung adds all patterns from different families, producing unusual values such as 125 points for Big Three Dragons and 155 for heavenly and earthly wins. Four Seas instead uses the principle do not add patterns already included. If pattern A necessarily implies pattern B in another category, B is not added because A's assigned value already includes it. The classification chart's notes identify such cases: Mirrored Sequences, for example, includes All Sequences. If A necessarily implies either B or C, or one of several other patterns, the value of whichever pattern occurs is added, because A's assigned value does not include those alternatives. All Odd, for example, necessarily combines with either All Triplets or Seven Pairs. All Odd plus Seven Pairs scores 60 + 40 = 100.

3. Winning requirements and payments

The Intermediate Edition distinguishes the self-draw minimum from the discard-win minimum. A hand must reach twenty points to win on another player's discard. A hand below that threshold but reaching the ten-point self-draw minimum can win by self-draw; thus all winning hands exceed ten points. Since self-draw accounts for only about one quarter of wins, the discard threshold effectively raises the overall winning requirement. Players should build toward twenty points, keeping the ten-point self-draw minimum as a fallback when a large hand cannot be completed or when defending. Self-draw is, after all, an entirely passive factor of luck.

Players in the same game may continue to use different winning requirements according to their skill. This allows experienced players to guide beginners while both play under relatively fair conditions. Each player uses their own winning requirement, and payments after a win use the lower score under the winner's rules or the paying player's rules.

For example, suppose the four players use levels I-A, I-B, II-B, and II-C. I-A wins the following hand by self-draw:

For I-A and I-B, the score is Two Similar Sequences twice, Half Straight twice, All Sequences, and All Simples: thirty points. For II-B and II-C, the higher interpretation is Mirrored Half Straight plus All Simples: sixty-five points. The actual calculation uses the lower, thirty-point interpretation, so the three opponents pay I-A a total of thirty points.

As another example, II-C wins this hand on I-B's discard:

For II-B and II-C, Three Shifted Sequences, All Sequences, and All Simples score seventy points. II-B therefore pays II-C fifty points, the payment threshold applied to a seventy-point hand. For I-A and I-B, only All Sequences and All Simples count, for ten points. Those two players pay according to that value: I-A pays ten, while I-B, as the discarder, pays 10 × 2 = 20.

This mixed-level format is intended simply to help experienced players teach beginners, rather than to provide a rigorously balanced competitive format.