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How to Play

Koi-Koi is a matching and capture game played with a 48-card Hanafuda deck. You are trying to capture cards that form scoring combinations (called yaku). The first to a higher total across the chosen number of rounds wins the match.

Match structure

  • A match is a fixed number of rounds, chosen in Options (1 to 12).
  • Each round produces an award for one player, or a draw.
  • The player with the higher total score after the last round wins the match. Equal totals are a draw.
  • A misdeal is not counted as a round.

The cards

The deck has 48 cards in 12 months of 4 cards each. Cards come in four types. Here is every card of each type, so you can learn them by sight:

Type Count Notes Cards
Brights 5 The most valuable cards. Used for the Bright yaku. 01-B Crane 03-B Curtain 08-B Moon 11-B Rainman 12-B Phoenix
Animals 9 Includes the Sake Cup (09-A). 02-A Warbler 04-A Cuckoo 05-A Bridge 06-A Butterflies 07-A Boar 08-A Geese 09-A Sake Cup 10-A Deer 11-A Swallow
Ribbons 10 Some are Poetry (red) or Blue ribbons, which form special sets. 01-RP Poetry 02-RP Poetry 03-RP Poetry 04-R Ribbon 05-R Ribbon 06-RB Blue 07-R Ribbon 09-RB Blue 10-RB Blue 11-R Ribbon
Plains 24 Mostly worth points only in bulk (Kasu). 01-P1 Plain 01-P2 Plain 02-P1 Plain 02-P2 Plain 03-P1 Plain 03-P2 Plain 04-P1 Plain 04-P2 Plain 05-P1 Plain 05-P2 Plain 06-P1 Plain 06-P2 Plain 07-P1 Plain 07-P2 Plain 08-P1 Plain 08-P2 Plain 09-P1 Plain 09-P2 Plain 10-P1 Plain 10-P2 Plain 11-P Lightning 12-P1 Plain 12-P2 Plain 12-P3 Plain

The Sake Cup (09-A) is an Animal, and it forms the Hanami-zake and Tsukimi-zake sets with the Curtain and the Moon (not in Tournament or Yakuza). The Rain Man (11-B) is a Bright, but it is not a wild card. See Cards for the special cards.

Here is one full month — January (Pine). All four share the same month, so any of them matches any other January card on the field:

01-B Crane 01-RP Poetry 01-P1 Plain 01-P2 Plain

January: Crane (Bright), Poetry ribbon, and two Plains.

Face-down cards (your opponent's hand and the stock) show the card back:

Card back

Matching is by month only. A card matches any field card of the same month. Card art, type, and name never decide a match. The Rain Man, Sake Cup, and Lightning cards are not wild.

Matching examples

Same month: capture. You play the January Crane onto a field that holds a January Plain. The months match, so both cards go to your pile:

01-B Crane played   +   01-P1 Plain on the field   → capture both

Different month: no capture. You play the same January Crane onto a field that holds a February Warbler. The months differ, so nothing is captured and the Crane stays on the field:

01-B Crane played   +   02-A Warbler on the field   → no capture

Full card list: Cards.

Setting up a match

Oya-gime: who deals first

Before the first round, each side picks from two face-down cards. The card with the earlier month wins the deal. If the months are the same, the higher card type wins (Bright over Animal over Ribbon over Plain). The winner is the dealer and plays first.

After the first round, the winner of the previous round deals. If the round was a draw, the dealer stays the same.

Dealing

  • 8 cards to you, 8 to the CPU.
  • 8 cards face-up on the field (the table).
  • 24 cards face-down in the stock (the draw pile).

Misdeals

If the field starts with all four cards of one month, or with exactly four pairs, the deal is void. The round is redealt with the same dealer, and the redeal is not counted.

Lucky hands

After a valid deal, the game checks each hand for a lucky opening:

  • Teshi: all four cards of one month in your 8-card hand.
  • Kuttsuki: four pairs in your hand (two of each month, four months).
Lucky hand Your 8-card hand looks like Result
Teshi (four of one month) Four January cards: 01-B Crane 01-RP Poetry 01-P1 Plain 01-P2 Plain plus any four other cards 6 points
Kuttsuki (four pairs) Two cards of each of four months: Jan 01-B Crane 01-P1 Plain · Feb 02-A Warbler 02-P1 Plain · Mar 03-B Curtain 03-P1 Plain · Apr 04-A Cuckoo 04-P1 Plain 6 points

A lucky hand wins the round immediately for 6 points, with no multipliers, and that player becomes the next dealer. If both players are lucky, the round is a 0–0 draw (except in Yakuza, where both players lucky is not a draw — the dealer wins 6 points (dealer privilege), see Yakuza).

Both are checked only once, on the 8 cards dealt at the start of the round.

Taking a turn

Each turn has two stages, and you always do both: a hand stage, then a stock stage.

Stage Where the card comes from Who picks it
1. Hand Your 8-card hand You, face-up, on the table
2. Stock The top of the face-down stock Nobody. It is turned over at random

A worked turn, in two steps (the field starts with a January Plain and no February card):

  1. Hand stage. You play the January Crane from your hand. The field holds a January Plain, so you capture both: 01-B Crane + 01-P1 Plain go to your pile.
  2. Stock stage. The top stock card is turned over: card back → 02-A Warbler. The field has no February card, so the Warbler stays on the field.

Stage 1: play a card from your hand

Pick a card from your hand and play it onto the field:

Field matches for that card's month What happens
0 The card is placed on the field. Nothing is captured.
1 You capture the played card and the matching field card.
2 You choose which one of the two matching field cards to capture.
3 You capture the played card and all three matching field cards.

If a card has a match, it must capture. You cannot put it down on the field while a match is available. You may play a non-matching card even when another of your cards would match.

Stage 2: draw from the stock

Reveal the top card of the stock and apply the same rules against the updated field. This includes the card you just played, if it landed on the field. The stock card never enters your hand.

If the stock card has two matches, you must choose one. You cannot cancel.

Scoring the turn, and calling Koi-Koi or Shobu

After both stages, the game scores the cards you have captured this round.

  • If your score has gone up since your last call this round, you are asked to choose:
    • In KK-ADD-10, the question opens when a combo is new or has grown in points instead — see KK-ADD-10.
  • Shobu (stop): the round ends and you score the award.
  • Koi-Koi (continue): play carries on, and you aim to score more. Your Koi-Koi call is recorded for the round.
  • If your score has not gone up, there is no prompt and play passes to the other player.
  • If you have no cards left in hand, Koi-Koi is not offered and the round ends automatically with your Shobu.
  • Some rule sets force a Shobu after your first Koi-Koi call. See each rule set page.

Example: calling Shobu or Koi-Koi. You capture the January Crane, the March Curtain and the August Moon. None of them is the Rain Man, so together they form Sanko (Three Brights). Under KK-ADD-10, Sanko is worth 5 points (see the Yaku table). Your score went up from zero, so the Koi-Koi screen opens:

01-B Crane 03-B Curtain 08-B Moon → Sanko, 5 points → choose Shobu to end the round and score 5, or Koi-Koi to play on and try for more.

Calling Koi-Koi is a bet. Each of your Koi-Koi calls raises your own multiplier, and the opponent calling Koi-Koi doubles your award if you win. See Multipliers.

Ending a round

The round ends in one of these ways:

  1. Shobu. A player stops and scores the award.
  2. A lucky hand (see above).
  3. Exhaustion. Both hands are empty and nobody called Shobu. This is a 0–0 draw and the dealer stays the same.

After a round, the results screen shows each yaku, the base points, every multiplier, and the final award.

Controls

A field card with its tooltip beside it, reading February / Plum, Plain / Kasu, Plain.

What a hover says: month and suit, type and its Japanese name, and the card's own name. The row is only armed on Easy (src/ui_main.c:569), and face-down cards cannot be described at all - a card registers itself for the tooltip as it is painted face-up (src/ui_board.c:179) and the back painter cancels the candidate by passing -1 (:187).

  • Play a card: drag a card from your hand onto the table, or click it once to select it, then click a matching field card. If it has no match, click an empty part of the field to place it. When two cards match, click the one you want; when three match, all three are captured. Small pointer movements still count as a click.
  • Selected card: the card and its matching field cards stay outlined. Click another hand card to change selection; click the selected card again, right-click, or press Esc to cancel. This click-selection outline works on every difficulty.
  • Inspect combos: click CPU COMBOS or YOUR COMBOS in the right column. The detail window shows completed combos, their points and cards, the base total, and current multipliers. Use NEXT / PREVIOUS for additional combos. CLOSE, Esc, or P resumes play; the CPU, animations, and turn timer stay paused while the window is open. The award preview is what that side would earn if it banked now, not points already awarded. The small panels show shortened previews; the window has the full names.
  • Choose a target: when a choice appears, click the card you want to capture. Some choices can be cancelled, and the stock choice cannot.
  • Pause: P, or Esc when no card is selected or being dragged.
  • Easy difficulty: hand cards that can capture glow, and while you drag a card, field cards of the same month glow to help you match. Hover over a face-up card for half a second to see its month/suit, type (including its Japanese name), and card name beside the cursor. This also works on captured cards and cards in choice overlays; face-down cards never reveal metadata. Tooltips disappear when you leave the card, drag, pause, or switch away from Easy difficulty.

Winning

Each round's award goes to the round winner. Points accumulate across the match, and the highest total at the end wins. The match result screen records the round-by-round ledger.

A 3 - 0 win over two rounds. The ledger is per round, not per turn, which is why the numbers are small even in a match where you captured half the deck each round.

Next steps