Five Hundred Help

Five Hundred Rules

These are the standard NeuralPlay Five Hundred rules. You may customize the rules to your liking as described here.

Five Hundred is a 4-player partnership game. You form a team with the player sitting across from you. The default 43-card deck contains the 5 through A in spades and clubs, the 4 through A in hearts and diamonds, and 1 joker.

The object is to earn points by bidding contracts and making them. A contract names a minimum number of tricks and either a trump suit or notrump. The team that wins the bidding becomes the declaring team for that hand; the other team defends and tries to prevent the contract from succeeding.

The game consists of multiple hands. Each team accumulates points as the hands are played. The game ends when a team reaches +500 or −500 points, and the team with the higher score wins.

Each hand consists of five stages: dealing, bidding, kitty exchange, play, and scoring.

Dealing

At the start of the game, the dealer is chosen randomly. The deal then rotates clockwise after each hand. Each player is dealt 10 cards, and 3 cards are dealt face down to the kitty.

Bidding

Bidding begins with the player to the dealer's left and proceeds clockwise. A player may make a bid or pass. A bid names the number of tricks the bidder's team promises to take, from 6 through 10, and a trump suit or notrump. For example, 7♥ promises at least 7 tricks with hearts as trump, while 8NT promises at least 8 tricks with no trump suit.

Every bid must outrank the previous bid. A higher level outranks a lower level. Within the same level, bids rank from low to high as follows.

Spades, clubs, diamonds, hearts, and notrump.

For example, 6♣ outranks 6♠, and every 7-level bid outranks every 6-level bid.

Suppose the bidding begins 6♦, pass, 6NT, 7♣. The 6NT bid outranks 6♦ because both are at level 6 and notrump is higher than diamonds. The 7♣ bid then outranks 6NT because a higher level always takes precedence. The next player must pass or bid higher than 7♣.

A player who passes may not reenter the bidding, and the current high bidder may not raise or change their own bid. Bidding ends when the other 3 players have passed. If all 4 players pass, the hand is passed out; no cards are played and no points are scored. The winner of the bidding is the declarer, and the winning bid becomes the contract.

The default introductory rules do not include nullo or open nullo. These special bids are an important part of many Five Hundred games. Once you are familiar with the introductory rules, you can enable them in Rule Options or select the Australian preset. Nullo is played as a notrump contract and indicates that the bidder will take no tricks. The nullo declarer plays without a partner. Open nullo is like nullo, except that the bidder's cards are exposed to the opponents during play. With the Australian preset's standard rankings, nullo ranks between the 7- and 8-level bids, and open nullo ranks between 10♥ and 10NT.

Kitty Exchange

After the contract is determined, the declarer takes the 3 kitty cards into their hand, then discards any 3 cards face down to form a new kitty. The exchanged cards are not shown to the other players.

Play

A hand consists of 10 tricks. Each trick contains 4 cards, 1 from each player. Every trick has a leader, a suit led, and a winner. The declarer leads the first trick. Thereafter, the winner of each trick leads the next.

Play proceeds clockwise. Each player must follow the suit led when able. A player who cannot follow suit may play any card. The highest card of the suit led wins unless a trump is played, in which case the highest trump wins.

In a suit contract, the joker and the 2 jacks of the trump color become trump. Cards rank from low to high as follows.

4, 5, 6, 7, 8, 9, 10, Q, K, A, left bower, right bower, and joker.

The right bower is the jack of the trump suit. The left bower is the jack of the other suit of the same color, and it belongs to the trump suit for the hand. For example, when hearts are trump, J♥ is the right bower and J♦ is the left bower. The J♦ belongs to hearts for the hand and is played as trump, not as a diamond.

In notrump, ordinary cards rank from low to high as follows.

4, 5, 6, 7, 8, 9, 10, J, Q, K, and A.

The joker is the highest card. When a player leads the joker, that player declares the suit led, and the other players must follow that suit when able. By default, a player following a trick may play the joker only when unable to follow the suit led. The joker wins the trick.

After all players have played, the winner gathers the trick and leads the next one. The cards in completed tricks remain available for review and for the optional card counter. Play continues until all 10 tricks have been completed.

Scoring

For a suit or notrump contract, the declaring team makes the contract by taking at least the number of tricks bid. If they succeed, they add the contract value to their score. If they fail, they subtract the contract value. The defending team receives 10 points for each trick they take.

Taking all 10 tricks is a slam. If the normal value of the contract is less than 250 points, a successful slam scores 250 points instead. A contract already worth 250 or more scores its normal value.

For example, making 7♥ adds 200 points to the declaring team's score. Failing 7♥ subtracts 200 points. If the defenders take 4 tricks, they also add 40 points under the default defender-scoring rule. A team that bids 6♠ and takes all 10 tricks scores 250 points for the slam instead of the ordinary 40-point contract value.

When playing with nullo and open nullo, nullo is worth 250 points. If the declarer succeeds in taking no tricks, 250 points are added to the team's score. If the declarer takes 1 or more tricks, 250 points are subtracted. The defending team receives 0 points. Open nullo is scored the same way but is worth 500 points.

After the hand scores are added to the teams' totals, another hand is dealt unless the game has ended. The game ends when a team reaches +500 or −500 points. The team with the higher score wins.

Web Links

Many websites discuss Five Hundred and its regional variants. Here are a few we found helpful.

• Wikipedia
• Pagat.com

Preset Game Rules

Five Hundred is played with many different rule options. NeuralPlay includes the following ready-to-play presets. See Rule Options to customize the rules.

• Australian (no nullo). Uses the standard rules described above with a 3-card kitty, multiple-round bidding, Avondale scoring, and a 500-point game. Nullo and open nullo are disabled to provide a simpler introduction to Five Hundred.
• Australian. The standard rules above with 2 additional contracts. Nullo may be bid after a 7-level bid, and open nullo may be bid anytime. Nullo is worth 250 points and ranks between the 7- and 8-level bids. Open nullo is worth 500 points and uses point-based ranking, with ties ranked higher.
• American. The Australian rules with a single round of bidding. The first 2 bidders may use 6-level inkle bids, which communicate suit strength but cannot win the bidding.
• Canadian. A single round of bidding begins at the 7 level. The 46-card deck contains all 4s and 2 jokers, and the kitty contains 6 cards. Nullo is disabled, though open nullo remains available. Defenders receive no points for ordinary tricks; when they set a contract, they receive its bid value instead. The game ends at +1000 or −1000 points, and the highest score wins when a threshold is reached.
• American (double nullo). American single-round bidding and inkle bids are used with a 5-card kitty. Nullo and open nullo may be bid anytime. Nullo is worth 250 points, open nullo is worth 350, and double nullo is worth 500. Double nullo may be bid only after the bidder's partner bids nullo or open nullo. In double nullo, both partners play and the team must take no tricks. The declarer exchanges with the kitty first, then the declarer's partner exchanges with the resulting kitty.

Learning Features

NeuralPlay Five Hundred offers many features to help you learn and improve your play. These features may be enabled, disabled, or adjusted in Settings. The features include the following.

• Hints. By default, the AI shows a hint when you ask for one. In Settings, you may ask the AI to always show a hint, or ask it to check your bid or play and show a hint only when its choice differs from yours.
• AI points estimate. When enabled, each hint shows the estimated number of game points that will be scored for each legal play. This is an expected value averaged across many simulations. The AI-suggested play may differ from the play with the highest estimate because of strategy or simulation noise.
• Card counter. When enabled, a counter shows which cards have been played.
• Analyze bid. When enabled, an "Analyze" button appears during bidding. Tap it beside a proposed bid to estimate the chance of making that bid.
• Competitive mode. Enable competitive mode to play without assistance. Hints, undo, viewing all hands, analyze bid, and other learning aids are disabled.

Rule Options

NeuralPlay Five Hundred offers many popular rule options so you can customize the game to your liking. The current custom rule settings and choices are described below.

Dealing

• Kitty size. Choose one of the following kitty and deck combinations. Each player is always dealt 10 cards.
  • 1 card, 41-card deck. The 5 through A of every suit plus 1 joker.
  • 2 cards, 42-card deck, no joker. The 4 through A in hearts and diamonds and the 5 through A in spades and clubs.
  • 3 cards, 43-card deck. The standard deck described above.
  • 4 cards, 44-card deck. The standard deck plus 4♣.
  • 4 cards, 44-card deck, no joker. The 4 through A of every suit, with no joker.
  • 5 cards, 45-card deck. The 4 through A of every suit plus 1 joker.
  • 6 cards, 46-card deck. The 4 through A of every suit plus the red and black jokers. The black joker is the higher joker.
• Highest joker in the kitty. Place the highest joker in the kitty before the remaining cards are dealt. This option is unavailable with a deck that has no joker.

Bidding

• Bidding rounds. With single-round bidding, every player has exactly one opportunity to bid or pass. With multiple-round bidding, bidding continues until only the winning bidder remains.
• Minimum bid. Begin ordinary bidding at level 6, 7, or 8.
• Inkle bids. Allow 6-level bids only for the first 2 bidders. An inkle bid communicates strength in its suit to the bidder's partner but cannot become the contract. If no bid of level 7 or higher follows, the hand is passed out.
• 6NT shows a joker. Treat 6NT as a conventional bid showing that the bidder holds a joker. This option is unavailable with a deck that has no joker.
• Allow nullo. Disable nullo, allow it after a 7-level bid, or allow it anytime.
• Allow open nullo. Disable open nullo, allow it after a 7-level bid, allow it after an 8-level bid, or allow it anytime.
• Allow double nullo. Disable double nullo, allow it only after the bidder's partner bids nullo or open nullo, or allow it anytime. Unlike nullo and open nullo, double nullo is a partnership contract: both partners play, and together they must take no tricks.
• Nullo ranking. Fix nullo between the 7- and 8-level bids, or rank it according to its selected point value.
• Open nullo ranking. Rank open nullo according to its selected point value and choose whether it ranks higher than, lower than, or equal to an ordinary bid with the same value. When bids rank equally, the bid made first has precedence. Double nullo uses this same point-based ranking rule.
• Nullo/open nullo receive kitty. Give the kitty to the declarer always, never, or only for nullo. With the last choice, open nullo skips the exchange; nullo and double nullo receive it. In double nullo, the declarer exchanges first and their partner then exchanges with the resulting kitty.
• Stick the dealer. If the first 3 players pass, require the dealer to bid so the hand cannot be passed out.
• Raise/change your own bid. After the other players pass, allow the current high bidder to raise the level or change the contract before bidding ends.
• Reenter bidding after pass. Disallow reentry, always allow it, or allow it only after the high bidder changes the contract. With the last choice, changing the suit or switching between a suit and notrump allows passed players to bid again; raising only the level does not.
• Notrump contracts. Use standard ace-high notrump, J5-style notrump in which the jack is the highest ordinary card of each suit, or disable ordinary notrump bids. J5 ranking does not apply to nullo contracts.
• Misdeal. Disable misdeals, or let a player call a misdeal during the first bidding round when their hand contains no aces, face cards, or jokers. The same dealer redeals, and the canceled hand scores no points.

Playing

• Initial leader. Choose the bidder (declarer) or the player to the dealer's left. In nullo or open nullo, a sitting-out partner is skipped.
• Notrump/nullo joker lead. When leading a joker, the player declares the suit led. Allow any suit, only a suit not yet led, only a suit in which that player has not been shown void, or allow the joker to be led only when no other card remains.
• Notrump/nullo joker follow. Allow a joker anytime, only when the player is void in the suit led, or as the first or last card for that suit. The first-or-last choice permits the joker the first time that suit is led or when the player has run out of that suit.
• Nullo must play joker when void. During a nullo-type contract, require a player who cannot follow suit to play a joker when the joker is legal.
• Jokers low in nullo. During nullo-type contracts, make jokers the lowest cards in the suits in which they are played.
• Finish hand early when determined. Stop play when the contract result and every score for the hand are already determined. Whether play can end early depends on the selected defender-scoring rules.
• Nullo claims are for no tricks. Interpret a claim by the nullo or open-nullo declarer as a claim that they will take none of the remaining tricks. When disabled, a claim means the player will take every remaining trick, as usual. This option does not apply to double nullo.

Scoring

• Scoring system. Choose Avondale, Original, or Perfect contract values.

• Nullo value. Choose the value of a nullo contract.
• Open nullo value. Choose the value of an open nullo contract.
• Double nullo value. Choose the value of a double nullo contract.
• Slam value. Score the better of the bid value or 250 points when the declaring team takes all 10 tricks, or always use the bid value.
• Defender scoring. Choose no trick points; 10 points per defending trick in ordinary contracts; or 10 per defending trick in ordinary contracts plus 10 points for each trick the declaring team takes in a nullo-type contract.
• When set. Subtract the bid value from the declaring team's score, or leave that team's hand score at 0 and award the bid value to the defenders.

Game Over

• Game over at. End the game when a point threshold is reached or after a fixed number of hands.
• Positive points to game over. Choose the positive point target.
• Negative points to game over. Choose the negative point limit.
• Hands to game over. Choose the number of hands to play. The team with the highest score after the final hand wins; a tie is possible.
• On reaching game over. When playing to a point threshold, choose one of the following.
  • Highest score wins. End the game when a team reaches the positive or negative threshold, and use the scores to determine the winner.
  • Must bid to win. A team reaching the positive threshold wins only after bidding and making the contract. If the declaring team reaches the negative threshold, the defenders win.
  • Declarers win when both teams over. Use the highest score normally, but if both teams cross the positive threshold on the same hand, the declaring team wins.
  • Defenders stop 10 short. Cap points earned as defenders 10 points below the positive threshold, requiring a team to make a contract to cross it.
  • Defenders stop 40 short. Cap points earned as defenders 40 points below the positive threshold.

Computer Players

NeuralPlay computer players offer six levels of play. Level 1 is reasonably easy and good for beginners. Level 3 should be fun for most players. Level 6 is the most challenging.

The computer players employ different AI methods depending on the level. Levels 1 and 2 use simple methods to provide an introduction for beginners. We will not describe them in detail here.

Level 3 uses a rule-based AI. The AI follows rules such as: "In third seat, do not trump partner's high card" and "In fourth seat, play just high enough to take the trick when an opponent is winning." We find that the rules work quite well and provide good play.

Levels 4 through 6 use Monte Carlo simulation to determine the best play. The AI deals out the unknown cards randomly. It then tries each legal play and plays the deal to the end to get a result. This is repeated for many deals of the unknown cards. The average result for each legal play is computed, and the play with the best average result is chosen.

Levels 4 through 6 differ in how many times the unknown cards are dealt out. In general, the more deals considered, the more accurate the simulation and the better the quality of play. The trade-off is that more deals take more time, so level 6 may play more slowly than level 4 depending on the device.

Since levels 4 through 6 do not use rules for card play, you may observe surprisingly good plays or odd mistakes that do not seem to follow a logical rule. Overall, our tests show that these levels play better than the rule-based level 3. We also find that the randomness makes the computer feel more human-like and fun.

If you prefer a more consistent, logical, and predictable partner or opponent, level 3 may be best.

Whichever level you choose, you may adjust bidding aggressiveness and nullo bidding aggressiveness. The nullo adjustment also affects open-nullo bidding. For individual control, choose Custom, which provides separate settings for North, East, South, and West. For each seat, you may adjust play thinking, bid thinking, bidding aggressiveness, nullo bidding aggressiveness, and open-nullo bidding aggressiveness. South's custom settings control the strength of the hints you receive.

We are continuing to research improvements and new computer AI algorithms. We continue to update the computer players as we develop improved algorithms.

Frequently Asked Questions

How do I change the hand sorting?

In Settings, choose Hand Sorting. You can change the rank order and suit order and choose whether to alternate red and black suits.

How do I reset the game settings?

On the main screen, open the menu and choose Reset.

What are North, South, East, and West?

You are always South, and your partner is North. East and West are the opposing team. The letters N, S, E, and W are abbreviations for these seats.

Why did the left bower appear to change suits?

In a suit contract, the jack of the same color as trump becomes the left bower and belongs to the trump suit. For example, when diamonds are trump, J♥ is a diamond trump for that hand, not a heart.

How are 2 jokers ranked?

The 46-card deck contains a red joker and a black joker. The black joker is higher. In a suit or standard notrump contract, both outrank the ordinary cards. The Jokers low in nullo option changes their position only during nullo-type contracts.

Why did my nullo partner not play?

Nullo and open nullo are solo contracts, so the declarer's partner sits out. Double nullo is different: both partners play, and the partnership succeeds only if neither partner takes a trick.

Why did our defending score stop below 500?

The default Defenders stop 10 short rule caps points earned while defending at 490. Your team must bid and make a contract to cross 500. You may change this behavior with the On reaching game over rule option.

What does claim mean?

A standard claim means the player expects to take all the remaining tricks. The app checks the claim before ending the hand. If Nullo claims are for no tricks is enabled, a claim by the nullo or open-nullo declarer instead means that player expects to avoid all the remaining tricks. That option does not apply to double nullo.

How do I contact NeuralPlay with suggestions and feedback?

Please email support@neuralplay.com.