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.