Project: Video Mahjong


I’ve been on a Riichi Mahjong kick recently thanks to some new found interest in the game amongst my friends. Playing the game has been a fun social experience for me. Of course you have to have three other willing players handy, a mahjong tile set, and a couple of hours to play a full game. Because of this, I can only have time to play on Friday and Saturday nights at best.

Arcade video game mahjong is something that I’ve been wanting to get running for years. It’s always been a super low priority in the past because I didn’t really know how to play the game at all until recently. One of my Egret II cabinets originally came with a mahjong control panel. It’s been in storage ever since I got it. Now with my mahjong interest and knowledge at an all time high, I want to get it running.

Video mahjong is hugely popular in Japan; the same way that video poker is quite popular in American casinos. There have been hundreds of video mahjong games made since the late 80’s. As long as the standard Japanese “candy” cabinet has existed (and even before that) there have been mahjong games for it.

The thing about mahjong, and what separates it from normal JAMMA arcade games, is the control method it uses. Instead of a joystick and buttons, it uses a long row of buttons that correspond to each tile in your hand, as well as buttons for each mahjong “call”.


Egret II mahjong panel with betting controls. This is the exact panel I have.


Drop in 3rd party mahjong panel with mahjong to JAMMA adapter built in. Manufactured by River Service for Sega candy cabinets.


Official Sega mahjong panels for Astro City cabinets.


Sega Astro City mahjong panel with betting controls.

The top row of buttons are lettered A to N, which correspond to each tile in your hand. Letter N is sometimes also labeled “Tsumo” (ツモ) which is what you press to draw your next tile. Not to be confused with calling tsumo for winning your hand. Press the button corresponding to the tile you want to discard.

The bottom row of buttons includes the betting controls and the “calls”. From left to right we have:
Flip Flop: Certain betting games allow you to swap your hand with your opponents if they declare riichi before you. This usually costs 1 credit to do.
Start: Starts the game.
Bet: Makes a standard bet in a betting game.
Take Score: Takes your winnings (instead of doubling up) in a betting game.
Double Up: Doubles your bet and plays again in a betting game.
Big: Essentially a double-double up or a full double up in a betting game.
Small: Essentially a half-double up in a betting game.
Last Chance: In some games, if you are in tenpai and lose, this button will allow you to draw one last tile. If you draw the tile you need, you win.
Kan: Call “Kan”. Can press after the other player discards if they discard a tile you can steal to make a kan, or you can press after you draw if you want to declare a closed kan (if you have one).
Pon: Call “Pon”.
Chi: Call “Chi”.
Riichi: Call “Riichi”. Most games allow you to call riichi even if you are not in tenpai. If you attempt to do this, the riichi will fail.
Ron: Call “Ron”.

Some games can be played with the standard joystick and button layout, notably Neo Geo mahjong games. If you are playing with this method, there are some other terms displayed on screen for different commands. In addition to the normal calls of pon, chi, kan and riichi, there are:
Tsumo: Draw your next tile.
Stay High: Discards a tile. Why it is referred to as this I have no idea.
Agari: Declaring a win. Automatically calls ron or tsumo where necessary.

So with all of these buttons (23 or 27 depending on if you are using betting controls), how can they correspond to the JAMMA inputs? JAMMA only has at most 20 allowable inputs, including the start buttons. We have to use a matrix input method, like a keyboard.


The mahjong board pinout and the mahjong multiplex matrix layout.

Just like how all JAMMA boards have the same connector, so do mahjong boards. Mahjong boards use the same 56-pin edge connector that JAMMA boards use, but the pinout is completely different. Why is it so different? Why not have the basic pinout the same as JAMMA? Voltage, video, audio, coin and test pins could be shared. I can’t say for sure, but my guess is that the mahjong board standard was invented around the same time as JAMMA (mid 80’s), but by a separate group of people. All mahjong boards conformed to this standard, and still do today, with the exception of mahjong games for cartridge/package systems. For example, mahjong games on the NAOMI system use a JAMMA pinout with the matrix inputs mapped to the button inputs.

In order to get a mahjong board working in my JAMMA cabinet, I need to make an adapter. The Egret II mahjong panel has the same 15-pin connector that plugs into the cabinet where the normal joystick/button panel plugs in. I need to trace the mahjong panel’s pinout to the JAMMA connector to find the equivalent joystick/button function. From there I can make a mahjong to JAMMA adapter.

Table that maps the mahjong function to it’s equivalent JAMMA function. This is for the Egret II specifically and may not work on other cabinets.

I will work on this adapter later. But for now, I still need to pick a mahjong board for my cabinet. Most video mahjong games are 1-on-1 where you play against a sexy female anime character. Typically you start with 1000 points and the opponent has 10000. You are supposed to progressively win in order to see risque pictures. While this style of mahjong is fun in it’s own way, I have opted for something a bit closer to real 4-player mahjong.

I won a Touryuumon PCB off of eBay for cheap. It was the cheapest mahjong board available, and it also might be the best.

$T2eC16hHJHIE9nysfrD9BRGRNdqkgg~~60_12 $T2eC16VHJGoE9nuQfe2QBRGRNgZIz!~~60_12

Touryuumon is a game by Yuki Enterprise that came out in 2003. There’s very little information about it online (that’s not in Japanese) but supposedly it was very popular in its heyday. Yuki Enterprise is known for Samurai Showdown V on the Neo Geo, and more famously the Arcana Heart series, after changing their name to Examu in 2006. Touryuumon did get a port to Xbox 360 later.

The problem with video mahjong from an operator’s viewpoint

A traditional game of mahjong can last from 30 minutes to 2 hours and beyond, depending on circumstances. Of course, even 30 minutes of gameplay for the typical 100 yen credit would not bring in enough revenue for arcades. The game needs to be sufficiently short, or have a way to keep the player paying additional money. This is why the 1-on-1 style game was invented, and why it used to be the most common form of video mahjong. Other games such as Pro Mahjong Kiwame features realistic 4-player action, but with special rules to keep the game short. For example, instead of playing a normal East/South game consisting of 8+ hands, it starts at South round 3, meaning you only play 2 hands. Additionally, bonus hands are not allowed.

Today, modern video mahjong in Japan is a lot different. The most popular games are Konami’s Mahjong Fight Club, and Sega’s MJ5R Evolution. These both use touchscreen interfaces, doing away with the old A-N control panel. In fact there are very few (if any) of the adult-themed, betting games around anymore. Japan has been adopting the idea of “Healthy Mahjong” recently, trying to shake off its negative image of a seedy underground gambling game.

These current games, as well as Touryuumon all play the traditional 4-player game with full rounds. To keep the game revenue flowing, these games have implemented a time system. When you draw a tile, your timer starts to count down until you discard. Once your time runs out, you have to pay more money to continue. You can also choose to pay more money up front to eliminate the timer completely. (You still have to make a move in 5 seconds if you’re playing online.)

Touryuumon has an online capability, but I’m not sure how it’s implemented. There is a standard RJ45 network port on the board. If there was once an online service offered, I’m sure it’s long gone by now. Could it possibly have a local network mode though? I’ll have to find out myself since I get no documentation with the board. Imagine playing 4-player video mahjong with your friends.

$T2eC16VHJGYE9nooiL8dBRGRNfC6HQ~~60_57 $(KGrHqFHJEIFENq)3sLnBRGRNeEufg~~60_57
The Touryuumon PCB. Ironically it is JAMMA and requires the included JAMMA to mahjong adapter. I then have to use my handbuilt adapter to convert from mahjong back to JAMMA.

One thought on “Project: Video Mahjong

  1. I really enjoyed reading this. I have a fascination with specialized, specific control schemes/input devices (rhythm games, Steel Battalion, etc) and you were super thorough and I learned a lot!


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s