In Four Humours, you are a doctor in medieval times, and everyone knows that your personality is determined by an imbalance of your bodily fluids, a.k.a., the four humours:

Choleric (Yellow bile) - Goal-oriented, decisive, ambitious.
Sanguine (Red blood) - Talkative, enthusiastic, social.
Melancholic (Black bile) - Analytical, detail-oriented, reserved.
Phlegmatic (White phlegm) - Relaxed, peaceful, easy-going.
The kingdom — composed of six map tiles with various locations — is filled with all types of personalities, from choleric sorcerers to phlegmatic peasants. ​Prove you're the best medieval doctor by visiting citizens throughout the kingdom so they can live out their life's ambitions...or lack thereof.

Each turn, you play a personality potion from your hand onto a citizen on a scene card to determining that citizen's personality. Each citizen can have one of two potion types played onto it, and you play each token face down so you know the personality of the citizen, but none of the other players do. Once all citizens on two of the scene cards are covered with potions, all potions are resolved in the following order:

A lone choleric wins, whereas two or more are discarded, after which...
Two or more sanguines win, whereas a single one is discarded, after which...
Exactly two melancholics win, whereas more than two are discarded and a single one sneaks away, after which...
Any number of phlegmatics win.
Place winning potions on the corresponding scene in the kingdom.. If a melancholic token sneaks away, place the potion on an adjacent scene connected by a path or bridge. After all potions have been placed, see whether you've completed any of the four randomized goals on display, such as having a potion on each of the six map tiles or occupying two pairs of locations that are connected by bridges. Then reveal four new scene cards and begin another round.

When a player completes an objective, the first party tile is resolved. Party tiles are similar to scenes with citizens, but they are available to play onto on your turn at any point in the game. Once the players at the table have completed six total objectives, the last party tile is resolved and the game ends. The player with the most objectives completed wins!

Alternatively, instead of using a shared kingdom board, you can play in "Fiefdom Mode", with each player having their own fiefdom board. After resolving scene cards, players place their winning personality potion covering a matching character in your fiefdom. The objectives now encourage you to cover all characters of certain types or to create a specific pattern within your Fiefdom.