Caravan (game)

Caravan is a card game designed by Obsidian Entertainment specifically for Fallout: New Vegas.

Inside of game
While traveling throughout the Mojave Wasteland, you will encounter NPCs who will be available to play a game of Caravan. In order to play Caravan you must possess a full deck (30+ cards), however the dialogue option appears even if you don't have enough cards. If an attempt is made to play with an insufficient number of cards, a message appears informing the player they need at least 30 cards to play a hand of Caravan.

Obtaining a deck and additional cards
A free 54 card starter deck and game instructions can be received from Ringo in Goodsprings. Additional cards can also be obtained from various merchants and corpses across the Mojave wasteland. If you find a merchant who sells you cards, check back with them periodically to see if their stock has refilled with any new cards. For example, Lacey in the Mojave Outpost seems to carry new cards somewhat often.

To add newly bought/found cards to your total card pool, place them into a container, press B to exit the container trade interface, then open the container again and use the "Take All" command. You will no longer see the cards in your Pip Boy inventory. Instead, they'll be listed in the bottom half of your deck creation interface the next time you play a hand of Caravan.

Note: If any of the cards are duplicates of cards you already found before, they will not appear in the bottom half of your deck creation interface. This explains why sometimes new cards that you've bought/found seem to disappear when you add them to your card pool.

Building A Deck
Caravan decks are composed of at least 30 cards from one or more traditional playing card sets. The deck may have any number of cards of any type that suits a player's strategy, although it cannot have duplicate cards from the same set. For example, a King of Spades from Set A and a King of Spades from Set B is acceptable, but more than one King of Spades from Set A would be illegal.

Rules
Caravan is played with two players building three opposing piles (or "caravans") of numbered cards. The goal is to outbid your opponent's caravan with the highest value of numbered cards without being too light (under 21) or overburdened (over 26). The game begins with each player taking eight cards from their deck and placing either one numerical card or ace on each caravan. Players may NOT discard during this initial round.

Once both players have started their three caravans, each player may do ONE of the following on their turn:

1. Play one card and draw a new card from his deck into his hand.

2. Discard one card from his hand and draw a new card from his deck.

3. Disband one of his three caravans by removing all cards from that pile.

Caravans have a direction, either ascending or descending numerically, and a suit. The suit is determined with the first card placed on the caravan, the direction by the second. All subsequent cards must continue the numerical direction or match the suit of the previous card. Cards of the same numerical value cannot be played in sequence, regardless of suit. Face cards can be attached to numeric cards in any caravan and affect them in various ways.

Card Values

 * Joker: Played against Ace; 2-10.
 * Effects change based on whether it's an ace or a number (see below). Multiple jokers may be played on the same card.


 * Ace: Value of 1.
 * Jokers played on aces remove all other non-face cards of the ace's suit from the table. e.g. a joker played on an Ace of Spades removes all spades (except face cards and that card, specifically) from the table.


 * Numbered Cards (2-10): Listed value.
 * Jokers played on these cards remove all other cards of this value from the table. Eg. a joker played on a 4 of Hearts removes all 4s (other than that card, specifically) from the table.


 * Jack: Played against Ace; 2-10.
 * Removes that card, along with any face cards attached to it.


 * Queen: Played against Ace; 2-10.
 * Reverses the current direction of the hand and changes the current suit of the hand. Multiple queens may be played on the same card.


 * King: Played against Ace; 2-10.
 * Adds the value of that card again. Eg. a king played on a 9 adds 9 to that pile. Multiple kings may be played on the same card for multiplicative effects; that is to say, a second King will add the doubled value resulting from the first King. So 4+King=8, but 4+King+King=16 (8 plus 8)

Winning
A player's caravan is considered sold when the value of its cards is over 20 and under 27. The other player may still outbid by increasing the value of their opposing pile while staying within the 21-26 range. When each of the three competing caravans has sold, the game is over. In the event of a tie between two matched caravans, the game continues until all three caravans have sold. The player with two or more sales wins the pot.

Clarifications
The official instructions are a little brief. For players having trouble playing, always seeing the card red when trying to add it to the caravan, note that you have to press DOWN in order to put it UNDER the caravan. A more thorough explanation can be found below.

Winning condition in plain English
Winning is easy to understand if you grasp the fact that the tech writer who wrote the official rules goofed a very important point of clarity: there are only three caravans on the board. Your three piles on your side are your bids for each caravan, and likewise for your opponent. Six bids, three caravans. As soon as all three caravans are sold, the game ends. The player who has the highest bid on at least two of the caravans at game end wins the pot.

A caravan is sold when at least one of its bids falls between the range of 21 - 26 AND the bids for that caravan are different amounts. Until all three caravans are sold, either player can keep adjusting the bids on any caravan! Only when all three meet the "sold" criteria does play stop and you determine who has two or more of the highest bids within the 21 - 26 range.

Now here's the tricky part: a caravan with tied bids (e.g. your bid and your opponent's bid add up to the same value; 25, for example) is not yet sold, so something must happen to break the tie. This can be done in many ways, such as: reducing your opponent's bid by playing a jack on one of the cards in their bid; playing a king on one of the cards in their bid to make their bid exceed 26; or say you're tied with 24 each and you discard for a few turns until you finally draw an ace and increase your bid to 25 to break the tie. Or say all three of your bids are 26 each but you opponent has one bid at 26 too, so that caravan is in a tied state. In this case you can simply wipe out your own bid (remove your stack for that caravan) and you'll instantly win the pot because the final caravan becomes sold, the game ends, and you'll have two winning bids to your opponent's one winning bid.

Opening
Each player starts out with 8 cards in his hand drawn from his deck. Players take turns placing their opening bids for each of the three caravans (i.e. columns on the table). To start a bid, a player must play any non-face card on the table, regardless of value or suit. Once both players have played their three cards regular gameplay commences. At this point there will be 3 columns and 2 rows of cards on the table.

Regular Play ('Contract War')
During a Player's turn, they can do one of the following:
 * Discard a card from their hand.
 * Discard one of their stacks from the table. (one of their bids)
 * Add to a bid. (Play a number card; i.e. Ace to 10)
 * Modify their bids or their opponent's. (Play a Face card; Jack, Queen, King or Joker)

Regardless of which option chosen, the player will draw a card afterwards, unless they already have eight cards in their hand.

Add to a Bid: Players add a number card (i.e. an Ace, or any card from 2 to 10) to one of their three columns and increase their bid. In order to add to a bid, a player plays a number card on the bottom of one of their stacks. The card must match the suit of the last card, or match the current direction. (ascending numbers or descending numbers) In both cases, the card must be a different value from the previous card.

Direction is determined by looking at the previous two cards in the column. At the beginning of the game, a player can choose to play a higher or lower value card, setting the Direction of the bid. Once there are at least two cards on a stack, those need to be checked to determine the current direction. Example: if there is a column consisting of "9-Hearts; 4-Spades; 3-Diamonds" then the direction is currently descending because 3 is smaller than 4. You could play any 2 card or any Ace. You could also play any Diamond card, except for 3-Diamonds.

Discard: A player can choose to discard either a card from their hand, and draw a new card, or discard a stack from the table. In either case, their turn immediately ends.

Modify a Bid: Face cards (Joker, Jack, Queen, King) have special abilities and can be attached, (Placed next to, rather than below) any number card currently on the table.

Example: played on a 7-Hearts this card will now be worth 14 points. If a second King is attached to it, it adds 14 (the total value) rather than 7, and the value would now be 28. Example: if there is a column consisting of "9-Hearts; 4-Spades; 3-Diamonds", attaching a "Q-Clubs" to the "3-Diamonds" means that you can now play any Clubs card, or any number card higher than 3. Example: When played against a 6-Spades, all other 6 cards regardless of their suit will be removed from the table. When played against an Ace-Diamonds all other Diamond number cards on the table will be removed.
 * King: Doubles the total value of the card(s) it attaches to.
 * Queen: Changes the column's direction and suit; an ascending bid becomes descending, and vice-versa. The bid's suit changes to match the suit of the Queen played. NOTE: The player can only play a Queen on the last card in the stack.
 * Jack: By playing this against a number card it acts as an eraser. The number card (and all its attachments) are removed from the table. This can be used on the player's bids to lower them from 27, correct a bad play made earlier, or to sabotage the opponent's bids.
 * Joker: Similar to a Jack, the Joker removes cards, but it does so on a larger scale. When played on a number card, all cards matching that number are discarded from play. When a Joker is played on an Ace, however, all cards matching the suit of the Ace are removed. The card the Joker is played on is 'spared'; it does not get removed from play.

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Miscellaneous strategies (some rely on exploits)

 * I have found that using only two suits is easiest. For example, I personally use hearts and clubs, remember to add in all kings, jacks, jokers, and queens. You should have about 30 cards. Next you try to play at least one of both suits, this can get tricky. If you have a ten and a king at the time, be patient and play your 10 first and when you've placed your first 3 cards, play the king on the 10, you will now be 6 away from a easy win. Also remember to use your jacks on "risky" looking stacks.


 * A deck will be most effective when it contains multiple ways to make totals between 21~26 quickly. The best combinations will revolve around Kings because one won't need to worry about playing cards in order as much.  For example, when playing the combo King-10-6, one can play TK6, 6KT, T6K, or 6TK to make 22 or 26.  Playing a combo like 10-9-7 requires one to play 79T or T97.  KT8 would be a combo similar to KT6.  In addition, T86 makes 24, a strong caravan as well.  A deck with a composition of five Kings, 10's, 9's, 8's, 7's and 6's would make a very strong 30-card deck (over 50% chance of drawing a playable 3-card combo to 22~26 when drawing 3 random cards).


 * My Winning Strategy, over 90 wins in a row and counting: Before the game begins you can discard and redraw as many times as you'd like. Abuse this ability to craft the following hand.  3 Kings, 3 8's or 10's and two 8's or 10's, whichever you don't have 3 of.  Whichever card you have 3 of use as the start of each of your bids.  Then the computer will play a card on one of his bids.  You play a second card on any other bid, he plays, you play on the remaining bid.  Then use your kings to double the 8's to 26 total and win the 2 bids you're on.  If you come into a tie situation remember that you can use a king to double one of the opponents cards to cause them to go over 26.


 * Kings are almost as useful to play on your opponent's caravans as your own. A well-placed king can overburden a winning bid (e.g. TK6 -> TKK6, making a caravan of 46. The opponent's best move is probably to discard the caravan!). Additionally, when you have two winning bids, you can often win by forcing your opponent to win the third bid.


 * Using this strategy makes the game very easy. Buy from vendors as many Kings, 10s, and Jacks that you can find - then put them all in your pack when playing. When laying down the three starter cards, keep discarding any card that isn't a King, 10, 6 and Jack. When you get a 10 - lay it down on one of the caravan. Try to have 3 Kings on your hand, one or two Jokers and some other cards from 2-6. So now you should have 10s (9s or 8s) on your three caravans. As the war starts, be as quick as possible to lay down Kings. If you strike out on drawing Kings you can also lay down 9 or 8. Very quickly now you will have 20 points on at least two decks. If you now notice your opponent having a good caravan you can use Jacks to take it out. All you need to do to win is lay down some (ideally) 6s on your 20pt caravans, but anything between 2-6 obviously works. Also keep in mind you only need to win two out of three caravans to win overall.

The strategy that i use to amass plenty of wins is make a deck of 10 8's 10 9's and 10 kings, 989= 26 9k8=26 8k9=25 898 = 25 this strategy will allow you to win on turn 7 almost all the time, you can also use the kings to send there bids over 26.

A simple strategy (relies on exploit)
All you need to win at caravan is three 10s three 9s and three 7s. Once the game has started continue to discard your hand till you have these cards. Now build two bids (10,9,7 or 7,9,10) ignoring the caravan the computer is paying attention to. Congratulations, you will now win every time in only 6 moves.

Criticisms of this strategy:
 * This strategy is weaker than many of the strategies in the preceding section because it has no cards designed to break a tied 26 value on two or more caravans. If the computer manages to tie one of the first two caravans you build to 26, that gives it time to then build a tied 26 value on two or all three caravans. In this case, discarding one of your bids might lose the game for you. You must have a way instead, to destroy up to two of the enemy bids in the even of a 26-26 tie on all three caravans.
 * This strategy (and many of the strategies listed above in the preceding section) will work somewhat well only as long as the game bug that allows you to discard during the initial round remains in place. As soon as the game is patched to prevent this bug, this strategy will be very weak.
 * This is not a strong strategy at all if you "play fair" now for roleplay purposes and do not abuse the "discard during initial round" bug.
 * There are other 3-card sets that can work better and faster in this particular strategy because you can construct a 7+9+10 in only two possible orders. Instead, there are three King-based sets can be constructed in any order: 10 +8/K or 10/K +6 or 9/K + 8.

Overview
Although Caravan is a fun way to make money in the game more reliably than by using the casino gambling games, it is not a balanced game for real world play because it's easy to construct a statistically "highest probable win" deck and gameplay method that cannot be countered except by an exactly similar "highest probable win" deck and gameplay method. Unlike other well-known and well-designed strategy-based card games in the real world (such as Magic:The Gathering), there is no metagame environment for Caravan, and no multiple counters to a statistically strong deck/gameplay strategy.

The deck construction and gameplay method described in this section is very strong against smart human opponents, and it utterly steamrolls all of the AI opponents that the original author has played so far in all the locations along the path from Goodsprings through New Vegas. I have a 32/0 win/loss record at level 6 and have never exploited the discard bug in the initial placement round--I always play the exact opening hand that I draw. I stopped bothering to save game before engaging a new NPC long ago, and don't bother saving until after I've bled them dry with 3-5 consecutive games. At level 6 I was sitting on 14k caps even after buying expensive stuff like That Gun, etc., so I ran up to New Vegas and plopped in 3 different S.P.E.C.I.A.L implants. And all this was accomplished without yet having the "Perfect" deck described down below, but instead using a less-than-perfect variant (also described below) that still has only 4 Kings and a mixture of 10s, 8s, 6s, and still one 9 at this point.

Did I mention that you don't need any exploits to consistently win with this deck and gameplay method? Win by the rules and feel good about earning those implants honestly!

Constraints that lead to a limited metagame
Note: Understanding the terminology (and concepts) used in Winning condition in plain English further up in this page is essential to understanding the terms and concepts used in the explanation of this strategy. (The author of this strategy was also the author of that section.)

The following facts about the rules and winning conditions of Caravan lead to a clear, single "highest probable win" deck build and gameplay strategy when you are playing by the letter of the rules and not exploiting gameplay bugs such as the current ability to discard from your hand during the initial placement round. The following three concepts are used often in the explanation of this strategy. A bid of 21-25 is called "winning bid" (WB). A WB that is higher than the competing WB on a single caravan is called a "high bid" (HB). Finally, a bid of exactly 26 is a called a "best possible bid" (BPB), because it cannot be beaten.


 * The fastest you can achieve a WB is with 3 cards, and the fastest you can achieve a BPB is also with 3 cards.
 * Because there is no speed difference between WBs and BPBs, achieving a BPB is always superior to a HB because a BPB cannot be beaten and it can force a "stalled win" state.
 * The fastest three-card BPB can be achieved with only four possible sets of cards.
 * 10 + 9 + 7, but this is a weaker choice that will be explained shortly
 * 10/K + 6 (king doubles the 10)
 * 10 + 8/K (king doubles the 8)
 * 8 + 9/K (king doubles the 9)
 * A BPB tie (26 to 26) on just one caravan or more effectively stalls the winning condition (called a "stalled win" state throughout this strategy) until either side manages to break all of the ties. This gives both sides time to discard as needed until they can build three HBs or BPBs for all three of their bids. The first player to reach a state of all HB or BPB for each of their three bids then simply needs to break the tied bids in a manner than leaves them with 2 HBs or BPBs versus only one HB or BPB for the opponent. This yields three possible end-game scenarios:
 * One caravan is in a tied BPB state (26 to 26) and you have the HB on the other two. If it's your turn, you have the "tempo sacrifice initiative" and can remove your BPB bid, instantly winning the game.
 * Two caravans are in a tied BPB state and you have the HB on the remaining caravan. In this case, there are two ways to win:
 * Destroy both of the opponent's BPB bids, or
 * Destroy one of the opponent's BPB bids and then before they can rebuild that bid back to a BPB tie again on that caravan, remove your BPB bid on the other caravan.
 * All three caravans are in a tied BPB state. The player whose move it is has a "tempo sacrifice initiative" and can instantly win by removing one of their bids.

The preceding bullets all point to one very simple goal for an optimum winning deck and gameplay strategy: every single card that appears in your hand must usable either for creating fast three-card BPBs on your side as soon as possible OR must be able to destroy your opponent's bids. This means:
 * You always want Jacks in your deck too, for extra destructive power (place on a high value card in an opponent's bid to make it drop below BPB/HB or even below any WB value at all.
 * Queens, Jokers, and 5 through Ace are all far less valuable because none of them directly contribute to a three-card BPB or to an ability to destroy an opponent's bid.
 * The three BPB sets mentioned above that use Kings are superior to the 10 + 9 +7 set in part because the Kings can do double duty: they can either contribute to a BPB on your side by doubling one of the numbered cards, OR they can be used to destroy an opponent's bid when necessary (by making their bid exceed 26). The King-based sets are also superior in that they remove any gameplay constraint based on card order. A 10 + 9 + 7 set can be built in only two possible orders (unless you're stacking suits, but that's impractical): 10 > 9 > 7 or 7 > 9 > 10. The King-based sets, by contrast, can be played in three possible orders regardless of suit. For example: 10 > 8 > K or 8 > 10 > K or 10 > K > 8

Basic deck design and gameplay method
The constraints in the preceding section lead to only three equally strong "highest probable win" deck designs, all of which use the same exact gameplay methodology:


 * 30 total cards, comprising only Jacks, Kings, 10s, and 8s, or
 * 30 total cards, comprising only Jacks, Kings, 10s, and 6s, or
 * 30 total cards, comprising only Jacks, Kings, 9s, and 8s
 * (prior to building one of the above three strongest decks) 30 total cards, comprising only Jacks, Kings, 10s, and 8s, with a supplemental mixture of 6s, 9s, 7s, and Aces (in that order of preference) that you remove as soon as possible (in reverse order) as you collect enough new cards to evolve towards one of the three strongest decks.

The trick, of course, is choosing the best total number of each of the four different cards in the strongest decks to ensure that your opening hand of 8 cards has the highest probability of being immediately useful for the initial placement round, but we'll expand on that aspect in a moment. First, let's summarize the gameplay method that confers the highest probability to flexibly win when you are playing fairly by the rules (i.e., not exploiting the current bug that lets you discard indefinitely during the initial round). This method is applied the same for all decks described in this strategy, including the less-strong variant that you're forced to start out with. The only effective counter an opponent has against these decks and gameplay method is to use exactly the same decks and gameplay method against you. Every other possible deck and method will be far less effective from a probability standpoint. As far as this author can tell, the game AI is not nearly "smart enough" to use anything like this deck construction and method against you, so you will easily beat the computer every time with careful play and no cheating needed, unless someone at Obsidian eventually patches in the heuristics behind this strategy to the game AI.

The gameplay method consists of four simple decisions at any move, in the following priority order:


 * 1) Priority 1: Stall your opponent from creating two unopposed WB, ideally by creating an opposing BPB yourself on that same caravan, or as a last resort only, by destroying one or both of their WB with a Jack or King.
 * 2) * Important: Always reserve three of your total number of Kings for use in your own BPB bids! For example, if there are 6 Kings total in your deck, you can use up to 3 of them to destroy enemy bids but then you must stop using Kings as destroyers. If you have both Jacks and Kings in your hand, always use Jacks first as your destroyers unless you've already placed 3 Kings onto your own bids.
 * 3) * Only destroy an enemy bid in the context of this "priority one" decision process under two specific conditions:
 * 4) ** When they have one unopposed WB and a bid of 11 or higher on any other caravan AND you cannot create a BPB on your side to counter their one existing WB. When this occurs, you must immediately destroy their unopposed WB, because if they pull a 10 on their next turn they might instantly win if the third caravan is already sold. (Or in some cases, they might also be able to win if they pull a King.)
 * 5) ** You have no cards in your hand that will contribute to creating a BPB on your side. In this case, it's almost always better to destroy/slow down their highest caravan rather than to discard a Jack or a King. The only exception would be when you have only Kings to use for this purpose but laying down a king on any of the opponent caravans would create a WP or BPB on that caravan--in this case, discard a King.
 * 6) * Note that by focusing on this priority in the early game you might actually win (and quickly) in a manner similar to Priority 3 below, by simply outbidding their early WBs with two of your own BPBs.
 * 7) Priority 2: If your opponent manages to create a BPB on any caravan, strive to create a "stalled win" state ASAP by creating a BPB tie on that same caravan (26 to 26). If you can achieve this stalled condition and maintain it (your opponent doesn't destroy your BPB on that tied caravan) long enough to get one or two more BPBs or HBs in place on your side, you will have a good chance to win the game if you can outpace your opponent on destructive moves per Priority 4 below. The main point here is that achieving and maintaining a "stalled win" if your opponent pulls off an early BPB will enable you to stop worrying about both Priorities 1 and 2, simplifying your decision process to thinking only about Priorities 3 and 4.
 * 8) Priority 3: Race to create 2 unopposed BPBs or HBs (not tied) on your side. The ideal goal is to win in 4 moves after the initial round ends. For example: you lay down three 10s in the initial round, and in the next four moves you lay down an 8 below two of those 10s and the double both those 8s with the King, while your opponent is trying to build up the other, third caravan. Net result: in four moves you have two BPB versus a WB or less on two of the caravans, and your opponent has a WB or PBP bid on the third caravan versus nothing on your side. This is a winning condition for you.
 * 9) * However, you must always balance this race for BPBs against the need to stall your opponent from getting too close to a winning condition per Priorities 1 and 2.
 * 10) * If your opponent foresees your ideal strategy and attempts to block it by creating a BPB tie (26 to 26) against one of your first two caravans to ''stall the win" in their favor, then the gameplay revolves around Priority 4 below.
 * 11) * While you are still playing with a sub-optimal deck (not one of the three strongest deck designs), it's sometimes possible to win quickly with a simple HB on the final caravan, so watch for these opportunities. Once you're playing with one of the three strongest decks, however, you stop thinking in terms of making HBs on your side because you can build an BPB just as fast and your entire deck construction revolves around cards that create only BPBs.
 * 12) Priority 4: Race to destroy tied BPBs on the opponent's side. Once you have at least one tied BPB (a "stalled win") plus two other BPBs or HBs on your side per Priority 3, then the end game boils down to a simple race to destroy all tied BPBs in a manner where the tempo works out in your favor and you pull the winning destruction move. Remember, there are three possible ways to win this "tie destruction race" as described further up in the section Constraints that lead to a limited metagame.

Detailed deck design
Okay so now that you know the generally ideal deck contents for the three possible "strongest" decks, and the gameplay method for winning with those decks, what is the ideal makeup of each deck, assuming you can collect all the necessary extra cards from various NPCs to build the ideal deck?

Goals of the optimum deck design
The basic idea is to load a 30-card (max) deck with a mix of Jacks, Kings, and ONLY TWO numbers (10s/6s, or 10s/8s, or 9s/8s) in a manner that yields three important highest-probability outcomes:
 * Between 3-6 cards in your opening hand of 8 cards must be numbered cards (not a King or Jack)
 * Anything fewer than 3 numbered cards and you lose tempo on the initial placement round. You must be able to place a card on all three caravans in the initial round to maintain opening parity with your opponent.
 * It's okay if you have up to 6 numbers cards all of the same number (e.g., six 8s), as long as the following outcome for opening hands is also met.
 * At least two cards in your opening hand must be capable of destroying opposing bids. This means two Jacks, or any combination of Jacks and/or Kings as long as you have at least 5 Kings in your deck. This ensures a two- to four-move tempo advantage over your opponent per the Priority 1 gameplay methodology above in case they get very lucky with their opening hand.
 * Within the first 12 cards drawn from your deck, you must have at least one BPB available to create on your side, to enable meeting Priority 2 if your opponent manages to create their own BPB by their move #5 (after you've exhausted your two destroyer cards in your opening hand). As long as you can create a "stalled win" state in response to an ultra-lucky 5th move by your opponent, you still have a very good chance of winning the game with proper play.

The preceding goals equally apply to the less-than-perfect deck you must start out with (described further below). All that's different is that the probabilities of meeting some of these goals are lower at first, but improve to optimum as you evolve your starter deck towards one of the three "Perfect" decks.

The "Perfect" deck
There are three possible "Perfect" decks that you can build. Pick one depending on which numbered cards you've collected and that you can add the most of to one deck. Ideally, however, I recommend that you gravitate towards a 10-8 deck because as you'll see in the section below about building a strong deck when you cannot yet build a "Perfect" deck, the numbers 10 and 8 have some special advantages.


 * 10-8 Deck:
 * Nine 10s
 * Nine 8s
 * Six Kings
 * Six Jacks


 * 10-6 Deck:
 * Nine 10s
 * Nine 6s
 * Six Kings
 * Six Jacks


 * 9-8 Deck:
 * Nine 9s
 * Nine 8s
 * Six Kings
 * Six Jacks

Each of these three "Perfect" decks yield 30 cards total with the following probabilities:


 * Opening Hand will contain at least 3 numbered cards = 95.8%
 * Opening Hand will contain at least 2 "destroyer" cards (Jack or "extra" Kings) = 87.8%
 * First 12 cards will contain at least one of each numbered card and at least one King to enable at least one BPB by your turn 5 = 97.1% each for the numbered cards, 86.9% for the King

Your opening hand will be ideal for winning at least 87.8% of the time. And even if you don't draw an ideal opening hand, you still have a very high chance of winning with proper gameplay prioritization even against a human opponent (and a virtually 100% chance of winning against the computer AI currently in the game). Every card you draw following your opening hand is 100% playable towards the the prioritized decisions of the gameplay method. There are no wasted cards and no need to ever cheat/exploit by discarding during the initial placement round. When you reach a state where you start discarding cards from your hand (usually only the numbered cards), it's because you've already rapidly built your three pairs of numbered cards needed to create winning BPBs on the three caravans.

Why only 30 cards max? This revolves around the cumulative probability works. In simple terms, the fewer cards in your deck, the higher chance you have of getting exactly the cards you want/need in your opening hand and with every draw thereafter.

How are the above probabilities computed? Computing card draw probabilities is tricky because with each new draw, the deck size decreases and the probabilities for the next draw change. For example, if in the "Perfect" deck you have a 60% chance of drawing a numbered card on the first draw from a 30-card deck, then on the next draw, the chance of pulling another numbered card from the remaining 29 cards depends on whether you pulled a numbered card in that first draw or not:
 * If you pulled a number on draw 1, you now have a 58.6% chance to pull a number on draw 2.
 * If you did not pull a number on draw 2, you now have a 62% chance to pull a number on draw 2.

This trend continues with each draw. So the technique is to calculate the average of all probabilities for each draw through 8 or 12 draws (per the important criteria for this strategy and gameplay method), and then use that average probability to calculate something called a "cumulative binomial distribution".

The strongest deck when you can't make the "Perfect" deck
Until you've visited enough traders to collect the cards needed to make the "Perfect" deck, your best bet is to use as many Kings, Jacks, 10s, and 8s as possible, then pad out the rest of the deck to 30 cards maximum with additional cards as follows:


 * 6s, 9s, and 7s in that order. When you are very first starting out with the deck that Ringo gives you, that will equate to 28 cards, so use four each of the preceding cards, then add two Aces to get to 30 total cards.
 * As you acquire new Kings, Jacks, 10s, 8s, 6s, and 9s, throw away the original "padding" cards in this order while still maintaining a 30-card deck: Aces first, then 7s, then 9s, then 6s. While you're still stuck with some Aces and 7s, your gameplay options will be less than perfect, but there are some tips below that can help you play around those Aces and 7s effectively.
 * When you can finally get rid of the Aces and 7s, the overall gameplay method described above will work very well for you, with the only real downside being that the odds of nailing at least one BPB by your turn 5 when needed (Priority 2) will be slightly lower than in the "Perfect" deck.

Gameplay tips with a less than "Perfect" deck:
 * Follow all the same basic priorities as for a "Perfect" deck, but with a few extra decisions as noted in the following bullets.
 * During your initial placement round, put down the 10s and 8s in your opening hand first if at all possible, because both can use two possible other cards to turn into a BPB! A 10 can be BPBed with either an 8 or a 6 plus a King, and and 8 can be BPBed with either a 10 or a 9 plus a King. By contrast, 9s, 6s, and 7s each have fewer ways to turn into a BPB. Try to never place an Ace during an initial round, and get rid of those Aces and Kings first as you acquire enough new 10s, 8s, 6s, and 9s to do so!
 * If you don't absolutely need to play an Ace or a 7 at any given point because your opponent is making weak choices and lagging in tempo compared to you, then discard it in hopes of drawing one of the stronger King/Jack/10/8/6/9 cards instead.

Bugs

 * Currently it's impossible to add purchased cards to the deck. Though this can be fixed by adding the cards to a container and then removing them from the container.
 * It is also difficult to select cards when editing your deck, because the card that's highlighted is often not the card you're selecting.
 * In game work around: Open any container or companions' backpack, put the cards from your inventory into the container or give them to your companion. Then close the container or end the trade. After this, open the container / companions' backpack again and get the cards back. The cards should now be added to your deck instead of being in your misc. inventory.
 * In some cases this workaround is impossible as, at least in my experience, the player is only capable of viewing the cards within their own inventory, when viewing a container or a companion's inventory the cards and deck are not shown, and it is therefore impossible to do anything more than throw them away.
 * Also it seems that the same bug is found on the US PS3 version of the game. Seeing as it sometimes causes the game to freeze when buying large amounts of cards from a vendor. The UK PS3 version also freezes when buying large amounts of cards. A possible work around is to first put all playing cards you already have in the backpack of a companion. Then buy the cards you want of a vendor and finally retrieve all already owned cards from your followers inventory.
 * Though the rules state no discarding may occur during the initial round, it is nonetheless possible to do so anyway. If you do, your opponent does not get a turn and you get to go again. By doing this you can stack your hand with whatever cards you want at the beginning and easily win every game.
 * After the game ends, when it says to press any button to continue pressing start and then hitting start again will cause the game to become unresponsive yet party chat still works.
 * It is not possible to discard cards from your hand once your main deck is empty. Your opponent will still be able to do so once their deck is gone.

Behind the scenes
The achievement name "Know When to Fold Them" is an homage to the song "The Gambler" by Kenny Rogers, specifically the well-known chorus: "You got to know when to hold 'em, Know when to fold 'em, Know when to walk away, Know when to run. You never count your money When you're sittin' at the table. There'll be time enough for countin' When the dealin's done."