Bridge — Rules

General

Contract Bridge is played by four players in two partnerships. You always sit South (bottom) and your partner North (top); the opponents are West and East.
A 52-card deck is used; everyone gets 13 cards. Ace is high, then King, Queen, Jack, 10 … 2.
The deal passes clockwise every hand. South deals first.

Auction

The dealer calls first and the auction goes clockwise. On your turn you make a bid, say Pass, Double an opponent's bid or Redouble when your side has been doubled.
A bid is a level (1–7) and a strain: ♣ Clubs, ♦ Diamonds, ♥ Hearts, ♠ Spades or NT (no trump). The level is the number of tricks over six: 4♠ = spades trumps, at least 10 tricks.
Each bid must be higher than the last: first by level, then at the same level ♣ < ♦ < ♥ < ♠ < NT.
Three passes after a bid end the auction; the last bid is the contract. If all four pass, the cards are redealt (same dealer, same vulnerability).
The first player of the contracting side to name the contract's strain is the declarer; the partner is dummy.

Play

The player on declarer's left leads. Then dummy's hand is laid face up; declarer plays dummy's cards.
If you are declarer, you play both your own cards and your partner's (dummy's) open cards. If your computer partner wins the contract, you play the hand: the table turns, your partner's (declarer's) cards move to the bottom, your own cards stay on top as dummy and you play both hands.
You must follow suit; if you cannot, you may play any card (you do not have to trump).
The highest card of the suit led, or the highest trump, wins the trick; the winner leads next. There are no trumps in NT.

Bidding system (option)

Natural (default): every bid means what it says; "1♠" really wants spades.
Conventions: the computer players use three common conventions; if you make the same bids your partner reads them as conventions too. Conventional bids are underlined in the auction with their meaning next to them.
Stayman: after partner's 1NT opening (no interference) 2♣ = "do you have a 4-card major?" (8+ points). Opener answers 2♦ none, 2♥ four hearts, 2♠ four spades.
Transfer: after partner's 1NT, 2♦ = "I have 5+ hearts", 2♥ = "I have 5+ spades". Opener bids the next suit (2♥ or 2♠), so the strong hand plays the contract.
Blackwood: once a suit is agreed, 4NT = "how many aces?". Answers: 5♣ 0 or 4, 5♦ 1, 5♥ 2, 5♠ 3. The asker then bids the slam or stops at the five level if aces are missing.

Contract points (per trick over six): ♣ ♦ 20, ♥ ♠ 30; NT 40 for the first, 30 for the rest. Doubled ×2, redoubled ×4.
Game bonus: if contract points are 100 or more it is a game: 300 non-vulnerable, 500 vulnerable. Otherwise a part-score bonus of 50.
Slams: small slam (6) 500 / 750 vulnerable; grand slam (7) 1000 / 1500 vulnerable.
Overtricks: undoubled at trick value; doubled 100 each (200 vulnerable); redoubled twice that. Making a doubled contract adds 50, redoubled 100.
Undertricks (scored by the defenders): undoubled 50 each (100 vulnerable). Doubled non-vulnerable: 100, 200, 200, then 300 each; doubled vulnerable: 200, then 300 each. Redoubled twice that.
Honours (to whichever side holds them): in a suit contract all five trump honours (A K Q J 10) in one hand 150, four of them 100; in NT all four aces in one hand 150. Honours count in both Chicago and Rubber.

Format

Chicago (4 deals) — default, the most popular form in the USA. Four deals, each scored separately. Vulnerability: deal 1 none; deals 2 and 3 dealer's side; deal 4 both.
Chicago (8 deals) — the same rules for two rounds (8 deals).
Rubber — the classic form. Contract points go below the line and accumulate; the first side to reach 100 wins a game and part-scores are reset. A side that has won a game is vulnerable. The first side to win two games wins the rubber: 700 bonus for 2–0, 500 for 2–1. No game or part-score bonuses in Rubber (the rubber bonus replaces them).

Result

At the end the side with more points wins; partners get the same result. Equal points is a draw.

Playing on KafaDinle.com

Computer players never cheat; they cannot see your cards or any hidden information.
Chance elements such as shuffling and dice use a secure random number generator and give no one an advantage.
Scored / Test: a scored game counts for the leaderboard of that game and level. Test games are not recorded anywhere; they have no move timer and undo can be enabled.
Points: at every level a win is +1, a draw 0, a loss −1. In 3–4 player games the sole winner gets +1, the last place −1, the others 0; a shared first place gets 0, a shared last place −1. Partners get the same points. The number of hands or target does not change this.
Move time: in a scored game you must move within the time you chose (chess 20–600 s, default 240 s; other games 30–600 s, default 180 s). A countdown is shown with a warning in the last 30 seconds. Tap the countdown to mute or unmute the warning sound. End-of-hand windows do not count.
Leaving the table: in a scored game the Exit button, starting a new game of the same kind, closing your account, losing the connection for more than 3 minutes, running out of move time and long inactivity all count as leaving:
Leaving in the first hand or in a one-hand game is a loss (−1).
Later, if you are in sole first place on the completed hands, no points are recorded; otherwise it is a loss.
In partnership games: if your team is ahead you get no points and your partner +1; if level, you −1 and your partner 0; if behind, both −1.
In chess the material is compared (pawn 1, knight 3, bishop 3, rook 5, queen 9): behind in material is a loss; level or ahead scores 0.
Resigning in chess counts as a loss.