Rules for Minefield Mahjong (17 Steps)

Invented by the great mahjong manga author Nobuyuki Fukumoto, Minefield Mahjong is a game that challenges your luck and intuition. It tests your ability to build a strong and subtle waiting pattern, and to uncover your opponent's wait. Though it was played on an automatic mahjong table in its manga appearance in Kaiji, the rules are easily adapted for play on a standard table, and those are the rules given below.

• Both players shuffle the tiles together, ensuring that all of the tiles are mixed incredibly well. Then, each player takes 34 tiles and builds a wall with them as in regular mahjong (While theoretically you should build two more walls as in regular mahjong, this step is unnecessary and can be skipped).
• If you built the two extra walls, the dealer chooses one tile on either of the side walls and flips it over. If you did not build the two extra walls, the dealer simply stacks one of the remaining tiles on top of another at random, and flips the top tile over. In either case, the revealed tile is the dora indicator, and the tile below it is the under dora indicator.
• Each player then looks at all of the tiles in their wall, not showing them to the opponent. They each use 13 of those tiles to build a hand for themselves. The only restriction is that your hand must be waiting (i.e., able to win immediately if one specific tile is added to it).
• Once both players have their ready hands, the dealer chooses one of the remaining 21 tiles from his wall and declares riichi while discarding it. Note that he is not allowed to add that tile to his hand before discarding (either to declare a win or to change his wait), and therefore no tiles are ever 'drawn' in Minefield Mahjong.
• If the other player did not win off of the discarded tile, he now discards one of his remaining 21 tiles while declaring riichi. The players then go back and forth discarding from their tiles until either player declares a win, or until both players have discarded 17 tiles.

 Aside from those basic rules, the following details are necessary for the game.

• A player is not allowed to declare a win if he is in furiten (by discarding one of his own winning tiles, or by neglecting to win off of the opponent's discard if he could), or if his hand is not at least a mangan (5 han).
• Though under dora can increase the value of the hand, it must be a mangan independent of any under dora. Regular dora can be counted towards the scoring of a mangan hand, though red dora are not used in the game.
• By convention, a hand worth at least 4 han and 30 fu, or 3 han and 60 fu, is counted as a mangan.
• If the opponent discards a tile that would complete your hand, but would not give you a mangan (such as a 1 when you have a 2-3 and need All Simples to score mangan), you are not permitted to declare a win and are put into furiten.
• Once a hand ends, the tiles are reshuffled and a new hand begins. If a hand ends in a draw, players do not reveal their hands to each other, and there is no chombo penalty for declaring riichi without a waiting hand.
• The game is considered to always be in the east round, so a pon of east wind is always worth a fan. The dealer is always considered as the east wind, and the non-dealer is always considered as the west wind.

 

SCORING RULES FOR MINEFIELD MAHJONG

• Except as noted below, Minefield Mahjong uses the same yaku as regular Japanese Riichi style mahjong.
• There is no way to have a kan in your hand, so there will never be kan dora. Additionally, the yaku 'Win Off of a Replacement Tile', 'Rob a Kan', 'Three Kans', or 'Four Kans' cannot be earned.
• The yaku 'Double Riichi' is disallowed by convention: Despite both players declaring riichi on their first discard, that is only worth 1 fan.
• If either player wins off of their opponent's first discard, One-Shot and Riichi will always be scored (even if the non-dealer wins off of the first discard, meaning they never technically declared riichi). For this reason, 'Gift of Man' is never scored.
• 'Pool of Dreams' and 'Eight Dealer Keeps' cannot be scored.
• Because players never draw any tiles from the wall, the yaku 'Fully Concealed', 'Last Tile Draw', 'Gift of Heaven', and 'Gift of Earth' are impossible to score. However, the dealer can score 'Last Tile Discard' if his winning tile is the 17th tile discarded by the opponent.
• If the hand ends in a draw or the dealer wins, the winds do not shift. If the opponent wins, they become the dealer for the next hand.
• No repeat counters are ever added to the table, and players do not bet any points for declaring riichi.
• Both players begin with 50,000 points. At the start of each hand, both players ante 1000 points to the winner. If a draw occurs, the ante doubles for the next hand (to 2000, then 4000, and so on). Once a player wins, the ante resets to 1000 points.
• A player who wins with a mangan collects that round's ante from the opponent.
• A player who scores a haneman (6 or 7 han) collects the ante, and the opponent pays an additional 50% of the ante (e.g., if there were three draws in a row and the ante was at 8000, the opponent would pay an additional 4000 points to the winner).
• A player who scores a baiman (8, 9, or 10 han) collects the ante, and the opponent pays an additional 100% of the ante (e.g., pays double).
• A player who scores a sanbaiman (11 or 12 han) collects the ante, and the opponent pays an additional 200% of the ante (e.g., pays triple).
• A player who scores a limit hand (13 or more han, or a natural limit hand) collects the ante, and the opponent pays an additional 300% of the ante (e.g., pays quadruple).
• A player who scores a double limit hand collects the ante, and the opponent pays an additional 700% of the ante (e.g., pays octuple).
• Once a player runs out of points, or cannot afford to pay the ante, the game ends and that player loses.