The four card categories — these are how many of each exist in the deck, not their point value: 5 brights, 9 animals, 9 ribbons, and 27 junk (23 plain + 4 "double junk," each worth 2 toward the junk count below).
Goal: play a hand card matching a table card's month to capture both. No match? It just joins the table face-up — and becomes free for anyone (including opponents) to capture later. Then draw the top deck card and it resolves the same way.
How each category actually scores (only counting cards you've captured): brights need 3+ to score anything — 3pts for 3, 4pts for 4, 15pts for all 5 (only 2pts if your 3 include December's "rain" bright). Animals and ribbons each need 5+ for 1pt, then +1pt per extra beyond that; ribbons also add a 3pt bonus for each complete 3-card matching-color set, and animals add a 5pt bonus for "Godori" (3 specific bird cards). Junk needs 10+ (a double junk counts as 2 toward that) for 1pt, +1pt per extra. Add all four categories together for your score.
The target — the score you need to be allowed to Stop — is 7 in a 2-player game, 3 in a 3–4 player game; it's shown live as "Target X/Y" next to each seat. Once you cross it, you must call Go (keep playing for more — score climbs sharply the more times you push it) or Stop (bank it now). The risk of Go: if anyone else wins the hand instead, every Go you called doubles what you owe (go-bak).
Bak penalties (stacking): if the winner scored from brights and you captured zero, or scored from junk and you captured fewer than 6, your loss doubles for each — on top of go-bak. Being behind and empty-handed on brights/junk is the expensive way to lose.
Bomb (💣): holding 3 of a month with the 4th on the table lets you sweep all 4 in one move, stealing a junk card from everyone — free value, always worth taking when offered.
Shake (🌀): declaring 3-of-a-month in hand doubles your final score if you win — pure upside if you were going to win anyway, but doesn't help at all if you lose.
Ppeok / Ttadak / Jjok: a 3rd card of a month stacks instead of capturing (ppeok) — risky, since whoever plays or draws the 4th sweeps the whole stack plus a stolen junk from everyone. Landing that 4th card yourself (ttadak) or drawing a match to your own just-discarded card (jjok) is the reward side of that same risk.
Full rules & scoring tables on Wikipedia →