Originally published on Cohost. I've ported the contents here and added a printable quick reference to use at in-person gatherings.

For selfish reasons, I’m proud to have zero games queued for three-player mahjong on both Tenhou and MJS. I consider the rule modifications to make the game work out with one fewer player as subtractive compromises from the regular four-player game.

Recently, however, I learned about a sanma variant that’s gained a bit of cult traction in Japan. Named after a floor rule violation where you accidentally shorthand yourself a tile, Shouhai Mighty (少牌マイティ) challenges you to replace the missing tile with, well, anything you can think of!

What makes Shouhai cool is that it embraces the juice of sanma to create a form of mahjong that’s fast and explosive, yet skill testing in a way totally unique from your typical riichi experience. Let’s try to figure out the wait of this sample tenpai hand:

The “bulging” 3445s should be a familiar iishanten shape for anybody who’s studied tile efficiency, so 2356s is one set of almighty waits, but there’s another pattern! The 11m44s tiles create an effective shabo wait, so your final wait is 1m23456s, six different tiles!

Here’s a more complicated example:

We’ve got a near-complete set of ittsu souzu tiles plus an entotsu pattern in pinzu, both complex waits. Considering all the different combinations, your wait is 11 tiles, 123456789s14p! If the above solutions seem confusing, try to work out what your almighty tile might be for every different possible wait.

If you want some full match example videos of Shouhai Mighty play, check out this tournament with spiffy production values, or this playlist consisting of several hours of lightly edited VODs.

The biggest impediment to the adoption of Shouhai Mighty outside of Japan, it seems, is two-fold: one, there are limited opportunities to play with Shouhai rules, and two, there are no English explanations for the format! While virtually no online clients directly support shouhai (although one MJS event mode did incorporate elements of it), the amount of in-person riichi has jumped significantly after people learned how to play mahjong during lockdown. Meanwhile, the rest of this post is going to attempt to enumerate the ruleset so you can learn and spread the gospel of the almighty tile. Try it out the next time your in-person meetup can’t form a full table of four!

Rules are sourced from the “official rules” and the ill-fated mobile game Syouhai Maitii. Use normal sanma riichi rules when not specified. Or don’t – every video I’ve watched on Youtube of jansou play uses their own unique blend of rules, so just call an audible with your playgroup if something seems wack. Make your own fun!

Printable Quick Reference Sheet (PDF)

Click through for full rules explanation

Shouhai Mighty Ruleset

The Almighty Tile

• Hands are composed of 12 tiles and one invisible “almighty” tile in your heart which can be treated as any tile
• Atozuke ari: The almighty tile is included in all yaku considerations (yes, that means you can still score Thirteen Orphans even when all 4 of an orphan has been discarded)
• Black five: The almighty tile is never considered a red five
• Karaten: The almighty tile can’t be used as a “fifth copy” of a tile if all 4 other copies are used in your hand

Game Setup

• Include 19m, all souzu and pinzu, and all honor tiles
• Include 1 red 5p and 5s.
• Flower tiles (4 total) are included as nukidora
• Autotable Setup
  • Set the autotable to use 112 tiles, building 4 walls of length 14x2 tiles each.
  • Each player constructs their starting hand by grabbing 3x2 tiles from the left and right sides of their wall.
  • Roll dice to determine who and where to break wall.
• Hand Shuffle Setup
  • Optional: include an additional 2x 5m as nukidora to normalize wall lengths
  • Set up 3 walls 19x2 tiles each.
  • Roll dice to determine who and where to break wall.
  • Deal out 12 tiles to each player in blocks of 2x2 each.
• Dealer draws a 13th tile; other players do not draw a tile
• [Tsumorikiri] No dead wall; draw up to the dora indicators. After kan, draw replacement tiles from the live wall.
• Optional: Gain an additional almighty tile instead of drawing a replacement tile
• From the end of the live wall, partition off 4x2 tiles to use as kandora, and flip the rightmost tile closest to the live wall as the initial kandora
• Uma is 10-20
• All players start with 30,000 points. Play continues after South 3 until one player reaches 40,000 points. Play ends when a player’s score drops below 0

Game Rules

• Chii calls are disallowed
• North is always considered yakuhai
• Nukidora tiles must be called and can’t be used to build your hand
• If the dora indicator is a nukidora tile, increase the value of other declared nukidora by +1 han
• Optional: Shuugi
  • Ippatsu, uradora, and kandora grant 1 shuugi (red fives do not, however)
  • Busting a player grants 2 shuugi
  • Yakuman grants 4 shuugi per player on tsumo and 5 shuugi on ron
• No end-of-round payments if noten
• No abortive draws besides four declared kans
• A missed ron call after riichi and mistaken ron/tsumo calls are considered chombo and incur a 5000-all point penalty

Riichi

• Open riichi is allowed and is worth 2 han
• Furiten riichi must be declared as open riichi and is only worth 1 han
• You cannot decline a win while in closed riichi (you may decline a win while in open riichi)

Local Yaku and Dora

• [Chiitoi] Using four copies of a tile for chiitoi is allowed
• [Sanpukou] Three triplets of winds is 2 han
• [Sanrenkou] and [Suurenkou] Three consecutive triplets is 2 han and four consecutive triplets is yakuman
• [Yonchoro] +1 dora for having all four copies of a tile in your hand (the almighty tile can be counted for this)
• [Otafuku] If you are not furiten and have a wait greater than 4 tiles, each additional wait grants +1 dora and shuugi (for example, a 5-sided wait grants +1 han and a 6-sided wait grants +2 han)
• [Mu] Winning after making 4 calls is considered Mu and is scored as yakuman. The player who dealt the fourth call is responsible for the yakuman payment
• [Manzu honitsu] is scored as yakuman
• [Closed honitsu chiitoi] is scored as haneman
• [Daisharin] Chinitsu chiitoi is considered Daisharin and scored as yakuman
• [Renhou] / [Blessing of Man] is scored as baiman
• Double yakuman are disallowed

Scoring

• Round up all fu to the nearest 10. Round up point calculations to the nearest 1000
• Each honba adds 1000 points to each player’s payment (example: 8000 ron becomes 9000 ron, 3000/5000 tsumo becomes 4000/6000)
• Optional: Each shuugi is worth 2000 points