Riichi
Also called: 立直
Japanese-only declaration: bet 1,000 points on a closed tenpai for guaranteed yaku.
Riichi is the signature mechanic of Japanese mahjong. When your closed hand reaches tenpai (one tile from winning), you can declare 'riichi!' by placing 1,000 points sideways into the pot. You gain a guaranteed 1 han bonus, a shot at ippatsu (1 more han if you win within one uninterrupted turn), and ura dora (extra dora indicators revealed at the end). But you commit to not changing your hand — you must discard everything that doesn't keep you in tenpai. Other variants don't have riichi.
- Ippatsu
Riichi-only: extra 1 han for winning within one uninterrupted turn after declaring riichi.
- Tenpai
One tile away from completing a winning hand.
- Yaku
Japanese-only term for a named scoring pattern. Every winning Riichi hand needs at least one yaku.
- Ura dora
Riichi-only: extra dora revealed only if you declared riichi and won.