What it is
A full Singapore-mahjong game that runs in a browser. Single player against AI, or online rooms against people. No download, no forced sign-up. You can open it and play as a guest, and it works offline.
I built it because the mahjong apps I could find either implemented a different regional ruleset or implemented Singapore rules badly, and mahjong is a game where “close enough” scoring is not a rounding error. It’s an argument.
The rules engine
Singapore scoring is the whole point, so the rules are treated like a reference implementation: one authoritative version of the rules everywhere the game runs, so the browser and the server can never disagree about a score. That discipline has caught more scoring bugs than any test I wrote deliberately.
Four rulesets ship, including Simple Old School with the full 144-tile set, and Experimental Chaos with twelve jokers, which is either an abomination or the best variant depending on who you ask.
The AI
Four difficulty tiers, and they differ in kind rather than in handicap. The lowest tier plays its own hand and little else. It chases a win and ignores you. The highest counts waits, reads the discard pile for what opponents are collecting, and defends ruthlessly, folding a live hand rather than feeding a dangerous tile. Building the top tier taught me more about my own play than several years at the table did.
Around the game
Online rooms run on Supabase Realtime. There’s a coins economy and a cosmetic shop: table themes, tile backs, and procedurally generated characters, so the cosmetics are code rather than an art budget I don’t have. Guest play needs no account; cloud sync is available if you want it, and optional if you don’t.
Where it stands
About 176 files, five months in and still active. The rules engine is finished. The AI’s defensive play is not, and probably never will be.