Riichi Mahjong Calculator, supporting features such as hand efficiency, meld hand efficiency, winning hand analysis, and score calculation for fan and minipoints. - Hand Efficiency: Includes tile efficiency, good-shape tile efficiency (for one-shanten only), and backwards strategy. - Meld Hand Efficiency: Tile efficiency for chow, pung, kong, and pass; includes good-shape tile efficiency (for one-shanten only) and backwards strategy. - Winning Hand Analysis: Defaults to Mahjong Soul/Tenhou rules, with customizable rules to some extent. - Score Calculation By Fan and Minipoints: Defaults to Mahjong Soul/Tenhou rules, with customizable rules to some extent.