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FAQ #25. Japanese Mahjong - Why Won't The Computer Let Me Claim Mahjong?

Latest update: August 26, 2014

Frequently Asked Question #25: "I downloaded a Japanese mahjong game, and I had a great hand going. My winning tile came up, but the computer wouldn't let me claim mahjong. What's up with that?"

There are two reasons this can happen.

There is a furiten situation (see below), or
You don't have enough fan, or you have no yaku (see below).

Note: Some computer games will let you claim mahjong despite a furiten or lack of yaku - when you do declare false mahjong, though, an error penalty applies. A penalty error is called chombo, and the penalty is that you must pay 8000 points : 4,000 to the dealer (oya) and 2,000 to the two non-dealers (ko). If you are the dealer, the penalty is 12,000 points: 4,000 to each of the three others. Your computer game may have an optional setting so you can choose to have the penalty apply, rather than have a penalty action merely disallowed. Some players might prefer a realistic penalty (in order to learn more effectively) and others might prefer a more leisurely play experience.


Furiten is from the Chinese, meaning "sacred discard." Authors Shozo Kanai and Margaret Farrell, as well as Eleanor Noss Whitney (see FAQ 3) all use the term in reference to a discarded tile, so I previously used the term that way too. But in 2007 I learned from Steve Johnson and Benjamin Boas that in Japan today, the term furiten refers to a state in which the player is forbidden to win on a discarded tile. Steve Johnson explains, "a hand is furiten if it can win on a previous discard, if it can win on a tile thrown previously this [go-]round, or if it can win on any tile thrown since riichi has been declared" (and not claimed by the player when initially thrown).

When a player's hand is furiten, the player must not win by discard, under penalty of chombo. Many Japanese computer mahjong games do not permit the player to do anything that would incur the chombo penalty... Thus inspiring the frequently asked question this article was written to answer.

The following text is largely based on the instruction manual for Activision's discontinued computer game Shanghai Dynasty (I wrote the text as an employee of Activision at the time), subsequently heavily edited and reorganized in May of 2007. First, let's examine the three different circumstances that create a state of furiten.

If you are playing a computer majan game using the Japanese rules, and the computer will not give you the chance to claim a discarded tile for a win, it could well be because your hand is furiten. Look at the discards and exposures and see if perhaps there is a "sacred discard" situation. If you find that this is the case, you can either discard in an attempt to get out of furiten or you can hope to self-pick the win, or you can switch to defensive play.

If your hand is NOT furiten, then perhaps the problem is that your hand simply doesn't meet the minimum fan requirement. A computer game that doesn't permit chombo due to furiten also won't permit chombo for any other reason, such as not having yaku.


In Japanese mahjong, you need to have a yaku (a special scoring element, which could be a tile pattern or a special way of going out) worth at least one fan minimum (iihan shibari) before you are permitted to declare a win. After the dealer has 5 markers (for having won 5 successive hands), the game's minimum win requirement goes from 1 Fan to 2 Fan (Ryanhan Shibari). Dora tiles (which include red fives) do not count towards the yaku requirement. Again, from the instruction manual for the Activision computer game Shanghai Second Dynasty (I wrote this)...

This FAQ was written mainly to answer the Frequently Asked Question, "Why wouldn't the computer let me declare mahjong in my Japanese majan program?" But of course other questions about Japanese majan also come up - like these from the the Q&A bulletin board...

Some related Japanese majan links:

  • For other details about Japanese mahjong, strategy, and to get definitions for terms used above, etc., there are several websites listed in FAQ 4b.
  • Want to play Japanese rules with only 3, or just 2, players? See FAQ 13.
  • Want to play Japanese rules with a mahjong set made for Japanese "Reach" mahjong? Go to Reach Mahjong: The Only Way to Play - Also a glossary, a monthly podcast, columns, discussion board, and a Ron2 tutorial.
  • A website where you can see the 26 episodes of "Mahjong Legend Akagi" (discussed in column 297 ): (thanks to David Willems)
  • Japanese rules, Japanese language. This is THE "reach" ("riichi") site for those who've graduated to playing online versus other human players (especially Yakitori Online members).

    Shanghai Dynasty manual © 1999 Activision
    FAQ © 2006-2020 Tom Sloper
    May not be reproduced.