Mahjong

How to play Mahjong (4-player, vs Computer)

Mahjong is a tile game for four players that grew out of centuries of Chinese card and domino games and is now loved across the whole of East Asia. Each player builds a hand of fourteen tiles made of four melds and a pair, drawing and discarding one tile at a time and claiming tiles their opponents throw away. This version seats you in the South chair against three computer opponents, and uses a clean, simplified-but-authentic ruleset: a 136-tile set with no flower or season tiles, the four standard ways to claim a tile (Pong, Kong, Chi and Ron), win detection for the classic “four melds plus a pair” shape (and seven pairs), and a small, clearly documented scoring table. The rules below describe exactly what this app does, so there are no surprises.

The goal

Be the first player to complete a legal winning hand of fourteen tiles — four melds (sets of three) plus one pair, or the special seven-pairs hand. You can finish by drawing your winning tile yourself (a self-draw, called Tsumo) or by claiming the tile another player has just discarded (called Ron). The hand you complete is scored, points pass between the players, and the deal ends. If the wall of undrawn tiles runs out before anyone wins, the hand is a washout (a draw) and no one scores.

The tiles

The set has 136 tiles: 34 different faces with four copies of each. The faces are drawn as original typographic inscriptions — the suit characters 筒 (dots), 索 (bamboo) and 萬 (characters) with a number, plus the wind and dragon characters — so no copied artwork is used. The three number suits behave exactly the same as one another; the winds and dragons are “honour” tiles that can only form triplets and pairs, never runs.

• Three number suits, ranks 1 to 9, four of each: Dots (筒), Bamboo (索) and Characters (萬) — 108 tiles in total. Only tiles of the same suit and consecutive numbers can form a run.
• Four Wind tiles — East 東, South 南, West 西 and North 北 — four copies each (16 tiles). Your seat wind and the round wind can be worth bonus points as a triplet.
• Three Dragon tiles — Red 中, Green 發 and White 白 — four copies each (12 tiles). A triplet or quad of any dragon always scores a bonus.
• There are NO flower or season tiles in this version — they are deliberately left out to keep the rules simple, so the set is exactly 136 tiles.

A turn: draw and discard

The dealer (East) starts. On your turn you draw one tile from the wall so that you are holding fourteen, then you must discard one tile face-up onto the table, returning to thirteen. Play passes to the next seat counter-clockwise: East, South, West, North, and around again. Instead of a normal discard you may, on your own turn, declare a concealed Kong (four identical tiles in your hand) or add a fourth tile to a Pong you have already exposed; either way you draw a replacement tile and then discard. When you draw the exact tile you need, you may declare a self-draw win (Tsumo) instead of discarding.

Claiming tiles: Pong, Kong, Chi and Ron

• Pong — when any player discards a tile you hold two copies of, you may claim it to make an exposed triplet. You take the tile out of turn, show the three tiles, and it becomes your turn to discard.
• Kong — if you hold three copies of a discarded tile you may claim it to make an exposed quad. A Kong draws one replacement tile from the wall (so a set of four still leaves your hand complete), after which you discard.
• Chi — a run of three consecutive tiles in the same suit. You may only Chi the discard of the player to your LEFT (the previous player). Show the two tiles from your hand that complete the run, and it becomes your turn to discard.
• Ron — if another player discards the exact tile that completes your hand, you may claim it to win immediately. That player alone pays you (they “dealt in”).
• Priority when several players want the same discard: a win (Ron) beats a Pong or Kong, and a Pong or Kong beats a Chi. If two players could win off the same tile, the one nearest in turn order takes it (a single winner). Anyone who does not claim simply passes, and the turn moves on.

The winning hand

A winning hand is fourteen tiles forming four melds plus one pair. A meld is either a triplet (three identical tiles), a Kong (four identical, which still counts as one meld), or a run (three consecutive tiles in one suit). The honours — winds and dragons — can only be used in triplets, Kongs and pairs. Melds you have already claimed count toward your four; the rest must sit concealed in your hand, and the tile you draw or claim completes the shape. The app also accepts the special Seven Pairs hand: seven different pairs, entirely concealed. Unlike some house rules, this version does NOT require any special pattern (“yaku”) to declare a win — any legal four-melds-and-a-pair or seven-pairs hand can win, which keeps the game friendly for newcomers.

Scoring

This app uses a small, exactly-defined scoring table rather than the full traditional count. Each winning hand has a base value of 20 points which is doubled once for every “fan” (bonus) it earns, capped, and multiplied by 1.5 if the winner is the dealer. The fans counted are:

• Concealed self-draw (win by Tsumo with no claimed melds): +1 fan.
• All simples (no terminal 1s or 9s and no honour tiles anywhere in the hand): +1 fan.
• Honour triplet: +1 fan for each triplet or Kong of a dragon, of the round wind, or of your seat wind.
• All triplets (every meld is a triplet or Kong, no runs): +2 fan. Seven pairs is worth a fixed +2 fan.
• Half flush (one suit plus honours only): +2 fan. All honours: +4 fan.
• Full flush (a single suit with no honour tiles at all): +4 fan — the biggest ordinary hand.

Payment is simplified with no fu, riichi sticks or bonus counters. On a Ron the single discarder pays the whole hand value. On a self-draw (Tsumo) the three opponents split it, each paying one third (rounded up). Scores can go below zero — there is no bankruptcy. These table scores appear on the game screen; the leaderboard, separately, awards a flat 10 / 30 / 100 points for beating the Easy / Normal / Expert computer, exactly like the other vs-Computer games.

Playing the computer (ranked)

You choose one of three difficulty levels before you start. The bots read their hands with a tile-efficiency heuristic: they keep tiles that already form or nearly form sets and pairs, throw away isolated honours and terminals, claim Pong and Chi when it clearly improves their hand, and declare a win whenever they can. Easy plays loosely with noisy discards so beginners can win; Normal plays a tidy efficient game; Expert claims more aggressively and keeps its hand better organised. The computer thinks entirely on your device, so the game works offline. Win a hand against the bots to earn ranking points — Easy +10, Normal +30, Expert +100 — and sign in to place your best result on the leaderboard.

Strategy tips

• Decide early whether you are going for runs or triplets. Number tiles in the middle (3–7) connect in many directions and are easy to build runs with; lone honours and terminals are only useful as pairs or triplets, so throw the ones you cannot pair up.
• Discard the tiles least likely to help you first. An isolated 9 or a single wind you do not need is usually a safer, more efficient discard than a middle tile that could still slot into a run.
• Claim with a plan. Calling Pong or Chi speeds up your hand but exposes it and can cost you concealed-hand value — only claim when the meld genuinely moves you closer to a complete hand, and remember Chi is only allowed from the player on your left.
• Chase the bonus. A triplet of dragons, of the round wind, or of your seat wind is worth an extra fan, and committing to one suit for a half or full flush is the surest way to a big score — but keep an escape plan in case the tiles do not come.

Frequently asked questions