About Riichi Arena

Last updated 6 November 2026

Riichi Arena is run by Oskar Engholm, a sole trader in Sweden. Questions, bugs and ideas go to [email protected].

What it is

• Riichi mahjong under the Standard rules.
• Made for a phone held in one hand. Works just as well on a computer.
• Free. No gacha, no ads, no characters, nothing for sale.

Features

• Rated games: matchmaking with players of a similar rating.
• Custom games: play friends through an invite link or practise against bots, choosing the bots' strength and the pace. No account needed to join a friend's game or to play the bots.
• Learn: a course from the basics to attack and defense.
• Train: drills on efficiency, waits, yaku and scoring, plus a daily set.
• Tutorial: a guided first game.
• Reference at the table: every yaku with its value, rule and an example hand, the core terms, and why a move isn't offered, in the game's menu, without leaving the game. As far as your hints allow, the yaku list also reads your own hand: what it wins with now, and how far each yaku still in reach is. In a game's replay it always does, for the seat you follow, at every step.
• Emotes: react at the table with a wave, a thumbs up or a laugh from the Emotes button, in rated games and in custom games with friends. A fixed set, no chat, nothing kept. Mute one player, or turn them all off.
• Analysis: a strong AI judges every decision a seat made in a finished game: an Accuracy for the game and a grade for each move, shown in the game's replay.
• Feedback: report a bug or suggest an idea from any page or table, with or without an account.

Fair play

Zero tolerance for cheating. See the Terms.