Push/Fold Decisions and Mahjong Payment Systems, Part I

An adversarial sport or game necessarily involves the interaction of offense and defense. A player can try to defeat the opponent or make sure the opponent cannot defeat them. The resulting contest can therefore end in a win, a loss, or a draw. Ideally, both offense and defense should be effective, creating a balance between the two.

Mahjong is an adversarial race

Except for Sichuan variants such as Bloody Battle to the End and Bloody River, most mahjong rules end a hand when the first player wins: the winner takes all. Mahjong is thus a race in which four players compete to complete a qualifying hand as quickly as possible. However, this differs from non-adversarial races such as running, swimming, and cycling; in those events, competitors cannot interfere with or make physical contact with one another, and are essentially competing against their own limits. In mahjong, four players share one set of tiles while each exclusively holds their own concealed tiles. They can claim chows and pungs or deal into another player's hand. They can, and quite reasonably should, use various means to impede opponents' hand building, readiness, and wins.

The closest parallel to mahjong as an adversarial race is neither a sport nor another traditional board or card game, but Mario Kart. Nintendo cleverly added ways for racers to attack and obstruct each other to what had been a straightforward racing game. This provided far more technical depth and entertainment than racing alone, producing the most successful racing game in video-game history. One obvious reason for Mario Kart's success is that adversarial games offer much more strategy and entertainment than non-adversarial ones. Running and swimming certainly have their own technical demands and embody the spirit of challenging one's limits. Nevertheless, the most popular sports remain adversarial events such as football, basketball, boxing, and tennis. As the saying goes, “There is endless pleasure in competing with others”: overcoming an opponent is part of human nature.

Mahjong has an inherent mechanism of strategic interaction that makes it distinctive among traditional board and tile games. Combining a race to build a hand with direct opposition is the fundamental source of its skill, strategy, and entertainment. Yet many regional variants restrict chows and pungs and permit only self-drawn wins. This weakens mahjong's most interesting element, its adversarial interaction, reducing it to a simple race. How different is that from playing alone? Regional mahjong often treats gambling as its main attraction and seeks to amplify luck. Simplifying the rules at the expense of interaction is understandable to some extent in that context. However, some people proposing improved rules repeatedly claim that mahjong lacks interaction, opposition, push/fold decisions, or even competitive merit. This misses the point and invites ridicule. (That is not this article's subject; it could be discussed separately if needed.)

Offense, defense, and push/fold decisions

The basic action in each mahjong turn is to acquire a tile and discard one, reorganizing the hand so it naturally advances toward readiness and completion. Offense primarily involves actively claiming chows and pungs to complete the winning structure faster. Defense primarily involves assessing the directions in which other players are building their hands and choosing discards that restrain or slow them, particularly the player to one's left. The contest continues from the opening to the end of the hand. Every chow, pung, and discard contains an offensive or defensive element: “Watch the player before you, keep an eye on the player after you, and guard against the player opposite.”

Unlike this continuous interaction throughout the hand, a push/fold decision is a specific assessment and choice. In the middle or late stages, players use exposed melds and discards to estimate whether an opponent is ready and how valuable that hand might be. They then consider their own hand and readiness to decide whether to keep attacking to win or defend to avoid dealing in. Many players encounter this concept through Japanese riichi mahjong, where an opponent's riichi declaration prompts a choice between pushing, cautiously preserving a chance to win, and folding. Most mahjong rules, however, have no special declaration of readiness such as riichi. Push/fold decisions are therefore more dynamic and uncertain.

Three main questions inform these decisions: Is the opponent ready? How much is the hand worth? Which tiles might deal in? Statistics for a particular ruleset can reveal the average turns on which players reach readiness and win, but these are only averages, with substantial variation. In an individual hand, the number of exposed melds is the most important evidence of readiness: more exposed melds generally mean a hand is closer to ready. Combining those melds with the opponent's discards, the discard pools, one's own tiles, and possible scoring patterns allows an estimate of hand value and dangerous tiles. For example, if the next player has exposed three bamboo melds, finished discarding honors, and begun discarding bamboo, they are probably ready for a Full Flush. Bamboo tiles are then dangerous, while characters, dots, and honors are relatively safe. Or if the opposite player has exposed two of the three chows that form a Pure Straight, that pattern becomes likely, and tiles for the remaining chow are dangerous.

Thus, all three elements—readiness, hand value, and winning tiles—are uncertain, but become clearer as the number of exposed melds increases. An entirely concealed hand may already be ready or even win, yet offer very little information for a push/fold decision. Mahjong inherently contains considerable luck, so these judgments cannot be completely certain; they are probabilistic.

Japanese riichi mahjong approaches these questions in almost the opposite way. Riichi explicitly announces readiness, settling the first question. The randomness of dora, especially hidden dora, makes the second question, hand value, indeterminate: it might be one han, a limit hand, or higher, making a payoff comparison difficult. A concealed riichi hand has no exposed melds to reveal its pattern or dangerous tiles, the third question. In other words, in riichi mahjong, readiness is certain while hand value and winning tiles remain uncertain. Together with full discarder payment, this has led to particularly strict furiten restrictions, including those based on one's own discards and temporary furiten, to compensate for the difficulty of identifying dangerous tiles.

Imagine two armies confronting one another. Riichi is like one side announcing: “Our weapons are loaded and ready to fire. We will not tell you whether we have rifle rounds, mortar shells, or howitzer shells, because we do not know either. But we can tell you that our previous impact craters are safe, as are the craters other players have made this turn. Decide whether to exchange fire or hide in the safe craters we have marked for you.” This is far removed from a real battle. In reality, one does not tell the enemy that a weapon is loaded; one conceals information and misleads the opponent. At the same time, one actively investigates the opponent's preparations, firepower, and direction of attack to make better offensive and defensive decisions.

Therefore, although riichi mahjong's extensive competitive development and large player base have produced deep research into push/fold decisions, riichi, dora, and furiten create a particular kind of decision-making. Its conclusions do not apply to mahjong rules in general.