The aim of the game is to score more points then your opponents with a set of three cards.
The game is played in several rounds, until only one player remains in the game.
Every round is structured as following.
At first, every player receives 3 cards. A starting player gets to decide, if they want to keep their cards or play them on the table to draw three new ones. If the three cards are kept, three cards from the deck will be drawn for the table.
From then players have the following options: exchange one handcard with a card from the table, exchange all handcards with the table cards, pass (if activated in gameoptions) or close the round.
Closing the round is only possible, when every player has played once. Then every other player gets to play an additional turn before the hands are evaluated.
In contrast to the usual game, once a player has a hand of 31 points, they automatically end the round and the evaluation is proceeded, leaving no last turn for the others.
The value of a hand depends on the gameoptions.
Gameoption "Only Color":
Cards are valued by Ace=11, King Queen and Jack are 10, or the value that stands on them.
If a hand consists of two or three card of the same color (that is club,spade,hearth and diamond), the values can be added.
Hence, the maximal value of a hand is 31. That's also the gamename in German (Einunddreizig) or French (Trente-et-un).
Gameoption "Color and triples":
Additionally to the option of collecting cards of the same color, a player can also collect a three-of-a-kind set of the same rank.
Such a triple is always valued 30.5 points.
Gameoption "Color or same value":
Additionally to the color also the values of same-ranked cards can be added, giving also the option to collect two cards of a rank to add them. However a hand e.g. 777 is valued 3*7=21, not 30.5. A hand AAA is valued 30, not 33 (if not playing with fire).
After the evaluation players lose virtual lives, depending on the gameoption. Players who have less then 0 lives are eliminated. So, when you have 0 lives left, you are still in the game (German "am schwimmen" which means swimming).
Then the game continues in the next round, if there are at least two players left.
Other gameoptions:
The number of cards can be set between 32, 36 and 52.
The number of lives per player can be set from 0 to 5.
If one playes with fire, a hand with AAA is valued 33 and causes an emmediate end of the round. Every other player loses a life.
Also check Wikipedia:
English: https://en.wikipedia.org/wiki/Schwimmen
German: https://de.wikipedia.org/wiki/Schwimmen_%28Kartenspiel%29