I first learned this game from Ralf Brostedt's page, which includes rules and a free computer version of the game.
- Players, cards and objective
- Deal, card exchange and making trumps
- Dropping out
- Scoring and Endgame
Players, cards and objective
The name of the game means "20 down". It is played by four people with a 32-card pack, the cards in each suit ranking from high to low A-K-Q-J-10-9-8-7. Each player starts with a score of 20 and the object is to be the first to reach zero.
Deal, card exchange and making trumps
The game is played clockwise. The dealer deals two cards to each player, and the player to dealer's left must choose a trump suit on the basis of his two cards. The dealer then deals three more cards each so that everyone has five cards.
Beginning with the player to dealer's left, each player may discard up to three cards (all at once) and obtain an equal number of replacements from the dealer. A player does not need to discard any cards at all if he is satisfied with his initial hand.
Now players have the option of dropping out of the play, if they do not wish to risk the penalty for taking no tricks. Each player in turn decides whether to stay in or drop out. However:
- The player to dealer's left, who chose trumps, must stay in (so the player opposite dealer has the first choice).
- If diamonds are trumps, everyone must stay in.
The cards are played out in five tricks, the player to dealer's left leading to the first trick. Players must follow suit if they can, and a player who has no card of the suit led must play a trump if possible.
Scoring and Endgame
The scoring works as follows:
- Players deduct one point from their score for each trick that they win.
- A player who stays in but takes no trick must add five points as a penalty.
- All the above scores are doubled if hearts are trumps.
- A player who drops out neither wins not loses anything.
If all players other than the trump maker drop out, then the trump maker wins all five tricks by default, and subtracts 5 points (10 if hearts are trumps).
If after eight deals have been played no one has reached zero, the rules change. The ninth and subsequent deals are played with hearts as trumps (so the player to dealer's left has no choice of trump suit). No one is allowed to drop out, and since hearts are trumps the scores are doubled.
The winner is the first player whose score becomes zero or less. If two or more players reach a score of zero or less on the same hand, the one with the largest negative score wins. If there is a tie for most negative score, further deals are played until there is a unique winner.
Alfred Jäger describes the following variant rules.
Some play with the card order from high to low J-9-A-10-K-Q-8-7 in trumps but A-10-K-Q-J-9-8-7 in the other suits, as in Jass games.
The initial deal is three cards to each player. The player to dealer's left has several options:
- to choose trumps on the basis of the first three cards
- to call "next" in which case the player's fourth card is dealt face up and its suit is automatically trumps
- to choose trumps "blind" (before looking at the three cards) in which case all scores for that deal are doubled
- if holding only 7's and 8's to demand a new deal - everyone throws in their cards and the same dealer deals again
When trumps have been chosen, the deal is then completed so that each player has 5 cards.
Players must decide whether to stay in or drop out before exchanging cards. Only those who commit to stay in can then discard up to three cards and obtain replacements.
The trump suit that forces everyone to stay in is clubs, not diamonds.
There must be at least two active players in each deal, so if all except the trump maker have dropped out, the dealer must stay in.
A player cannot drop out of two consecutive deals: anyone who drops out is forced to stay in on the next deal.
A player whose score is 5 or less cannot drop out.
There is no special endgame. The game continues for as many deals as it takes until someone reaches zero.
From Ralf Brostedt's site you can download a Zwanzig Ab program for Windows.
FestApp has published a 20-down Android app.