R Mahjong is a complete implementation of the Japanese version of Mahjong, otherwise known as riichi mahjong.

For instructions on how to play, please follow this link
http://riichimahjong.net/rules/

Features:
*The rules are basically identical to the standard Japanese rules (with open tanyao, red fives, atozuke ari, and double ron).
*Real and fast artificial intelligence.
*Maximum possible tile sizes for easy reading.
*Several interface languages supported (English and Japanese).
*Recording and playback of game (step-by-step and automatic modes). Review is
possible from point of view of any player.
*Display of gamer’s playing progress (rating).
*Types of advertizing switchable according personal preferences.
*Completely free.
*LAN play (via Wi-Fi). You can play with any combination of people and bots.