Main conventions:

Kuitan – ari – open tanyao is allowed.
Aka – nashi – no red fives are used.
Kuikae – ari – switching chi is allowed, but you can not discard the same tile you’ve opened on
Atodzuke – ari
Double yakumans – nashi – no double yakumans.
Pao – ari – the player who discarded the tile in the last set of daisangen/daisushi/suukantsu is responsible for the whole payment, if the yakuman was made by tsumo, and for the half of the payment, if the yakuman was made by ron.

Prizes:

Challenge Cup winner.
Prizes from sponsors.