Why Mahjong Tiles Make a Great Roguelike Deckbuilder
How Outlaw Mahjong turns 108 tiles into a mahjong roguelike deckbuilder: instant small hands, no plain flush, rarer patterns worth more, a deck you reshape.
A roguelike deckbuilder needs three things: a pool of pieces with clear identities, a scoring rule that rewards some combinations over others, and room for the player to reshape that pool over a run. Mahjong has been refining the first two for well over a century. Outlaw Mahjong is our attempt to add the third, and to build a mahjong roguelike that feels like a natural fit rather than a theme pasted onto playing cards. Here is why hands are small, why there is no plain flush, why rare patterns pay the most, and how upgrading and removing tiles turns 108 fixed tiles into a mahjong deckbuilder you build yourself.
A deck that already has a story
The wall in Outlaw Mahjong is the 108 number tiles of Chinese mahjong: Characters (万), Dots (筒) and Bamboo (条), ranks one to nine, four copies of each. Three times nine times four is exactly 108, which is also the number of outlaws in the Water Margin, so the novel's heroes had a ready-made home.
The more important number for game design is four. A deck of playing cards also has four copies of each rank, but they are split across four suits, so any two cards of the same rank form a pair. In mahjong a pair means two tiles that are completely identical, same suit and same rank. That makes pairs roughly twice as hard to find as in a poker deck, and it shifts the whole hand ladder. Runs become the backbone instead: a chow (three in a row in one suit) is far easier to find than a pung (three identical tiles), and four identical tiles become a genuinely rare event.
Each tile also carries its own chips: its face value, from 1 to 9. A scoring 9 is worth nine times a scoring 1, so even before any upgrades, the rank of every tile matters.
Small hands, instant scoring
Traditional mahjong is a race to complete a fourteen-tile winning hand, and most turns score nothing. That works for a four-player table game, but a roguelike needs constant feedback: every decision should produce a number you can read.
So Outlaw Mahjong scores small plays immediately. You hold thirteen tiles, the same as a hand in Sichuan or Chinese Official mahjong, and up to four times per blind you play one to six of them. The game finds the best pattern in what you played and scores it on the spot. You also get three discards per blind to throw away one to six tiles and draw replacements. Tiles that are not part of the pattern still leave your hand, but they add no chips.
The patterns are built from the same pieces as a real mahjong winning hand: melds and pairs. A meld is either a chow or a pung, and the two count the same. From weakest to strongest the nine patterns are High Tile, Pair, Meld, Two Pairs, Meld + Pair, Three Pairs, Two Melds, Kong and a hidden Five of a Kind, and the hands made of two or more groups can also come in a Pure, one-suit version. Meld + Pair and Two Melds are a real winning hand in miniature, which is part of why the game feels like mahjong even though nobody is building fourteen tiles. You can read the full table on the how to play page.
Why there is no plain flush
A flush hand seems like an obvious thing to borrow from card games, and we considered it. The numbers ruled it out. With only three suits, a random thirteen-tile hand contains six tiles of the same suit about 66% of the time. A plain flush would be available in most hands, so it would either be worth too little to matter or crowd out every other decision. So one suit only pays on top of a real hand, a nod to mahjong's 清一色 (pure one suit): when Two Pairs, Meld + Pair, Three Pairs or Two Melds are all in one suit, the hand gets +4 mult. We made it a flat +4 rather than doubling the mult because one suit hits pair hands much harder than meld hands. Three Pairs drops from 26% of hands to 3.3% when it has to be one suit, while Two Melds only drops from 24% to 7%, since a chow is one suit already. Doubling would have made Pure Three Pairs cheaper than the more common Pure Two Melds.
Instead, suit matters through heroes and tile upgrades. Heroes such as Zhang Shun and Ruan Xiaoqi add mult for every scoring Bamboo or Dots tile, and tactics that change a tile's suit let you push the wall toward one suit on purpose. Some bosses punish exactly that: Gao Qiu debuffs every Bamboo tile, Tong Guan every Dots tile and Cai Jing every Characters tile. Stacking a suit is a strategy with a real cost, not a free pattern you trip over.
Rarer hands are worth more
Every pattern has base chips and a base mult, and the score is chips times mult. We set those values from simulation: we drew thirteen random tiles forty thousand times and recorded how often each pattern was present. In a default thirteen-tile hand:
| Pattern | Chance in 13 tiles | Base chips × mult |
|---|---|---|
| Pair | 93.6% | 10 × 2 |
| Meld | 73.5% | 20 × 2 |
| Two Pairs | 65.1% | 25 × 2 |
| Meld + Pair | 63.5% | 35 × 3 |
| Pure Two Pairs | 32.9% | 25 × 6 |
| Pure Meld + Pair | 28.7% | 35 × 7 |
| Three Pairs | 26.0% | 85 × 3 |
| Two Melds | 24.0% | 60 × 5 |
| Pure Two Melds | 6.9% | 60 × 9 |
| Pure Three Pairs | 3.3% | 85 × 7 |
| Kong | 0.4% | 100 × 8 |
The rule is simple: from Pair up to Kong, Pure versions included, when two patterns' odds differ by more than three points, the rarer one is always worth more. Patterns within three points of each other count as one tier, and then we look at how easy each is to chase. Three Pairs and Two Melds are dealt about equally often, but pairs are easier to dig for: after one discard you have Three Pairs 63% of the time against 56% for Two Melds, and after three discards 93% against 88%. So Three Pairs scores 255 at level 1, below the 300 of Two Melds. A Kong shows up in about one hand in 250, so its base value is forty times that of a Pair. An automated test re-checks this ordering whenever the odds change.
Formation cards level a pattern up for the rest of the run, adding chips and mult each time. That is where the deckbuilding begins: a player who keeps seeing Melds can invest in Melds until they outscore the rare hands they are not drawing.
Building the deck: enhancements and seals
The wall starts as 108 plain tiles, but between blinds you can change almost everything about it. Silk-bag tactics, bought in the shop or found in packs, do most of the work.
Enhancements
Each tile can hold one enhancement:
- Gold: +¥3 if it is still in your hand at the end of a blind.
- Jade: ×1.5 mult when it scores, with a 1 in 4 chance to shatter afterwards and leave your deck for good.
- Iron: ×1.5 mult while it stays in your hand.
- Dice: when it scores, a 1 in 5 chance of +20 mult and a 1 in 15 chance of +¥20.
- Wild: counts as any suit when the game checks for a chow or a Pure hand.
- Stone: no suit or rank, a flat +50 chips, and it always scores.
- Cinnabar: +4 mult when it scores.
Iron changes how you read a hand: a pair of iron tiles held back multiplies every play you score, so sometimes the best pair is the one you keep.
Seals
A tile can also carry one seal. A red seal retriggers the tile when it scores, a gold seal pays ¥3 when it scores, a blue seal creates the formation card for your last played pattern if the tile is still in hand at the end of a blind, and a purple seal creates a random tactic when the tile is discarded. Both of the last two need a free consumable slot.
Thinning the wall
The quietest deckbuilding tool is removal. With 108 tiles and only four copies of each, every tile you cut raises the odds of the ones you keep. One tactic deletes two tiles outright. Sun Erniang removes a tile from your deck for good, and pays you ¥2, whenever you discard exactly one tile. Even jade's shatter chance thins the wall over time.
Combine removal with copying and suit changes and the wall starts to look nothing like a fresh set: fewer suits, more duplicates, the identical tiles a pung or Kong needs. Copying is also the only way Five of a Kind can appear, which is why it stays hidden until the first time you play it.
Where to start
The fastest way to see these pieces fit together is a run. Play Outlaw Mahjong in the browser, read the tile guide if the suits are new to you, and meet the heroes of Liangshan before you recruit them.