Gamehelpkoikoi

About yaku (card combinations)

You can use the in game help icon to display a popup listing all the possible yaku and how many points they are worth.

All the yaku are combinative, except the "Bright" cards yaku, which are exclusive (you will always score the biggest available).

As is often the case with traditional games, there is a lot of variants for playing Koi-koi, especially in regards to scoring.

For Board Game Arena, two variants are provided through the options when creating the game:

Soft "Koi!" is a variant adapted from the Sloperama site rules which is all about saying "Koi!". Of course you run the risk of your opponent making a yaku and scoring for the month (round) before you can score yourself, but in exchange for that risk, each time you will get a multiplier so that if you manage to increase your score with another yaku, you will score a lot more. Also, a starting multiplier will be set for the month if some "Bright cards" have been drawn for the field when dealing for the month. So this is an aggressive variant with a lot of points available if you push your luck.
Hard "Koi!" is a variant adapted from the Hanafubuki site rules which is less incitative to call "Koi!" since you won't get a multiplier just for saying "Koi!". Instead, your opponent will! If you say "Koi!" at least once, then if your opponent manages to score his score will be doubled. Still, at some point you'll risk it, because if you manage to improve your yaku to score 7 points or more, then your score will be doubled.