About

Riichi Mahjong is the competitive Japanese ruleset that turns the familiar tile-matching game into a genuine game of skill, risk management, and hidden information. You sit at a table of four, drawing and discarding tiles each turn as you race to build a complete hand: four sets of three (or four) matching or sequential tiles, plus a pair. This version seats you against three AI opponents, so a real match is always available.

What separates Riichi from casual mahjong is the layer of declared intent. Once your hand is one tile away from winning (tenpai) and fully concealed, you can declare "Riichi" — locking your hand, betting a stick, and broadcasting to the table that you're close, in exchange for a guaranteed extra yaku and a shot at bonus dora tiles on the next draw. From there it's a tense wait: win off your own draw (Tsumo) or off an opponent's discard (Ron), or fold quietly and feed nobody a winning tile.

Scoring runs on han (yaku value) and fu (fine-grained hand composition points), which combine into point totals that swing dramatically — a cheap hand nets a few hundred points, a loaded one with multiple yaku and dora can end the game outright. The settings panel lets you toggle red fives, restrict calls like chow and pung, or require self-drawn wins only, so you can dial the ruleset toward exactly the table you want to play.

How to Play

• Each player starts with 13 tiles (the dealer draws a 14th to begin) and takes turns drawing one tile, then discarding one.
• Build a complete hand of four sets — three matching tiles (pung), a run of three consecutive tiles (chow), or four matching tiles (kong) — plus one pair.
• Call "Chi," "Pon," or "Kan" to claim a discarded tile that completes a set, or pass and keep drawing normally.
• Declare "Riichi" when your hand is fully concealed and one tile away from winning, locking it in exchange for bonus scoring potential.
• Win by declaring "Tsumo" on your own drawn tile or "Ron" on an opponent's discard, provided your hand contains at least one valid yaku.

Tips

• Watch which suits and honor tiles opponents are discarding — it tells you what they're likely not collecting, and what's dangerous to feed them.
• Don't rush to declare Riichi with a weak wait; a hand waiting on many possible tiles is far more likely to actually win.
• Defense matters as much as offense — once an opponent riichis, consider folding by discarding only tiles you know are safe rather than chasing your own hand.

History

Mahjong originated in China in the 19th century and spread to Japan in the early 20th, where it evolved a distinct competitive ruleset now known as Riichi Mahjong. The modern rules were standardized after World War II and codified further through professional leagues, becoming a fixture of Japanese arcades, manga, and anime — with titles like "Akagi" and "Saki" built entirely around its scoring and psychology. Online platforms such as Tenhou and later Mahjong Soul brought the ruleset to a global audience in the 2000s and 2010s, and it's now widely considered the definitive competitive form of the game, prized for the tight interplay between building a hand and reading the danger of every opponent's discard.