Strategy

Hand building

Generally speaking, Mahjong allows only drawing, discarding, and calling tiles, which means that the basic options are not complex. In Japanese Mahjong, it is frequently beneficial to keep the hand closed, that is, to refrain from forming melds through calling tiles. Because of the requirement for a winning hand to fulfill at least one scoring condition ("have at least one Yaku"), indiscriminate tile calls can easily lead to a hand that is virtually impossible to rescue. In particular, calls for sequences involving terminal tiles (1 or 9) should be evaluated carefully. The reason is that the three simplest and most common Yaku, Riichi, all-simples, and the no-points hand, all become impossible by such a call. Building toward specific, rarer hands usually makes sense only if the hand drawn initially is well on its way towards completion. In these cases, tile calls are often essential to have a realistic chance of completion.

Defensive play

Players begin to get an idea of the hands of other players through two main mechanisms: open melds and discarded tiles. The discarded tiles are visible for everyone and remain associated with each player. On average, the safest tiles to discard are wind tiles that are neither seat nor round wind. All honors tiles have the advantage that they play very limited roles, so the discard tableaus will give good hints if, for example, a particular dragon tile is safe to discard. In the standard suits, terminal tiles are, on average, safer to discard than central tiles because they can complete fewer sequences and because they need to be avoided for several Yaku. Later in a hand, the hopes to complete one's own hand might be so small that the priority becomes to avoid discarding tiles that lead to a Ron call. In a bad hand, it might be worthwhile to discard dangerous tiles early and hold on to safer tiles. Avoiding discards that complete hands is nearly as important as winning hands in Japanese Mahjong.

Furiten

The discard tableau plays another important role: a tile that would complete a player's hand found among the discards means that that player is in a state called Furiten. In this state, the player cannot win a hand by Ron. This rule has the very useful consequence that discarding a tile that is found in someone else's discards is always a safe defensive play against that player. Similarly, the rule means that it is unwise to change frequently the sets targeted for one's own hand. In doing so, the discard tableau will inevitably fill up with many different and unrelated tiles, which increases the chance of being Furiten and makes it easier for other players to discard tiles.