Each player is dealt 8 cards and 8 cards are placed in the middle. A player goes first. If a instant winning hand is dealt it is scored and a new round is started. Otherwise play as normal.
On your turn, you can capture a card in the middle with a card from your hand. Those cards must be of the same month. If you do, take the card you captured with the card you played and place them in your winning zone. If not, you must discard a card and place it in the middle.
Then, draw a card from the deck and capture using it. If it cannot capture any cards you must discard it.
Besides, if there are 3 cards from the same month they are placed in a stack. The player with the last card from that month can captures all of them.
If you form a yaku you must either score it or shout koi-koi. If you score it, you get those points multiplied by the multiplier and the round ends. If not, the round continues and you cannot score that yaku until you have formed another yaku. Do note that if your opponent scores a yaku, you lose your points.
End the game after a number of rounds (or months). At the end of the game, the player with the most points (or kobans) wins!
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 incentive 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.
Please also note how draws are handled:
- - if a month ends by lack of cards in hand and no player has managed to form a yaku, the dealer for the month (first player) gets 6 points ("dealer's privilege");
- - if a month ends by lack of cards in hand and at least a player managed to form a yaku (and said "Koi!" to continue), it's a draw and nobody gets any points.
About "Viewing" yaku
A few variants have been implementend for the "Viewing the Moon" and "Viewing the Cherry Blossoms" yaku:
- - Viewing yaku enabled : both yaku are available (this is the default)
- - Rain ruins the party : if a player captures at least one card of November (rain), the party is ruined, both yaku are unavailable for this player
- - Viewing yaku disabled : both yaku are unavailable.
About "First play"
Getting the first play (and thus being the first to choose from the field) is a nice advantage. Some variants have been made available upon request:
- - Winner starts the next month : the winner for the current month gets to play first the next month (this is the default)
- - Loser starts the next month : the player who lost this month gets to play first the next month
- - Alternate starting player : the player who didn't get to play first this month will play first the following month.