Riichi is the Japanese branch of the four-player game, and the one that most often reaches western players sideways, through a manga or an anime series where someone slams a tile down and announces something. That announcement is the riichi declaration itself, and it is a genuine commitment rather than a flourish: the hand it comes from is locked from that moment until it wins or the wall runs dry.
What the set looks like
Riichi uses 136 tiles. The flowers and seasons of a Chinese set are absent, so what remains is three suits of nine ranks in four copies, four winds and three dragons in four copies each. Many sets replace one of the four fives in each suit with a red-marked copy, and those red fives are bonus tiles worth an extra point of value when they appear in a winning hand.
The structure of a hand is the familiar one, four sets and a pair, and the turn is still draw one, discard one. Everything distinctive in this school sits on top of that foundation rather than replacing it.
The yaku requirement
This is the rule that surprises players coming from Hong Kong style. A hand of four sets and a pair is not, by itself, a winnable hand. It must also contain at least one yaku, a named pattern from a fixed list, or it cannot be declared at all. A player can be sitting on a complete fourteen tiles and be unable to do anything with them. Marine Mahjong is one of the layouts kept on this site.
That single requirement reshapes the whole game. You are not racing to complete any structure, you are steering towards a structure that qualifies, and the cheapest way to guarantee one is to keep your hand concealed and declare riichi, because riichi is itself a yaku. Calling tiles from discards is therefore expensive in a way it is not in Chinese play: an open hand has to earn its pattern some other way.
The riichi declaration
You may declare riichi when your hand is concealed, is one tile away from completion, and you have at least a thousand points to stake. You place a thousand-point stick on the table, and from then on your hand is frozen: every tile you draw must be discarded unless it wins the hand or extends a set you already hold in a legal way.
The trade is information for value. The whole table now knows you are waiting, and good opponents will play defensively against you. In exchange your hand gains a yaku, gains value, and gains access to the hidden bonus indicators described next, which is why the declaration is the engine of the format rather than a last resort.
Dora, the bonus that decides scores
Before play, one tile on the dead wall is turned face up. That tile is an indicator, not the bonus itself: the bonus is the next tile in sequence after it, so an indicator showing a three of circles makes every four of circles in a winning hand worth an extra unit of value. Winds and dragons follow their own cycles.
Dora do nothing for the structure of a hand. They will not complete a set and they cannot substitute for a yaku, which is the mistake newcomers make constantly. They only multiply the value of a hand that was already legal. A player who declares riichi and wins also flips a second, hidden indicator underneath the first, so the final score often jumps well above what the visible tiles suggested.
Furiten, the rule that catches everyone
Furiten forbids you from winning on a discard when the tile you need already sits in your own discard pile. If your hand can be completed by a two of bamboo and you discarded a two of bamboo earlier, you may only win by drawing it yourself.
It applies to every tile your hand could accept, not only the one you have in mind, so a hand with several waits goes furiten if any one of them has passed through your discards. It also applies temporarily if you decline a winning tile, lasting until your next draw, and permanently if you have declared riichi and let a winning tile go by. This is the single most common way a strong hand quietly becomes worthless, and it is why players count their own discards as carefully as everyone else’s. The site’s own example of it is Mahjong Firefly.
Why it is called the strict school
Stack the pieces together and the picture is clear. Every hand needs a qualifying pattern. The declaration that most easily supplies one costs you all further choice. Your own discards can lock you out of winning. Scoring is a two-axis calculation of han and fu rather than a doubling table, with dealer and non-dealer paying different amounts and self-draws splitting three ways.
The compensation is that the game is unusually well defined, which is exactly why it exports. Tournament bodies in Europe and elsewhere run championships on written riichi rules, and the large online platforms have introduced far more players to the school than tile sets ever did. Those platforms do not all agree in the details, so a habit learned on one service can be illegal on another: whether open hands may be built from simple tiles, whether the dealer may end the game while ahead, and how three-player variants handle the missing suit are all rule-set choices rather than fixed law. A layout of that kind in the catalogue here is Mahjong Relax.
If you want the branch this one grew from, the Chinese sequence covers the wall, the claims and the faan scoring it replaced. The American game went in the opposite direction, abandoning free-form patterns entirely, and the map of Mahjong types places all of them beside the solo boards. The catalogue index here is the single-player side of the family, which shares the tiles and none of this machinery. Mahjong Duels puts that layout on a playable board.
