What are the rules of Caravan?

You're right that both the in-manual and in-game introductions to Caravan are not very effective. This is what I figured out via a combination of trial-and-error and the instructions.

(Also, I keep the Caravan rules card from the deck that comes with the special edition out when I play New Vegas. Very handy quick-ref for the face cards once you get used to the rest.)

The basics:

2 players play the game. You can use any cards you want, as long as (a) you have at least 30 cards in your deck and (b) no two identical cards (EG, 2 of clubs) come from the same casino. (In real life, if you wanted to play, they couldn't be the same deck/brand. Unless you frequent casinos enough to have a collection. :)

The game combines elements of blackjack, war, double-solitaire (that is, two player head-to-head solitaire) and even Uno.

Each player is initially dealt 8 cards. Your first three plays to the board must set up your initial caravans -- you have three to set up. Give them each a numbered (ace through 10) card. During these plays, you can discard any cards from your hand that you like, drawing a replacement card from your deck. Cards you discard are gone from play -- so don't discard your good ones. Discarding at this stage is required if you are dealt eight face cards and/or jokers.

Each of those caravans has a suit and a direction. The suit is the suit of the last numbered card dropped on the pile. The direction is either up or down from your starting point. An important thing to note (and I had to lose about a dozen hands before I learned this) is that the direction does not have to be sequential -- you do not, for example, have to follow a 10 with a 9, or a 5 with a 6. You can have the following sequence (which adds to 26): 10, 9, 7.

To play a numbered card on one of your caravans, it must either be going in the appropriate direction, or it must be of the same suit as the last numbered card. However, under no circumstances can you play the same number twice in a row, no matter what suit they are.

You're targeting a range of between 21 and 26 (inclusive) for each your three piles.

Gameplay

During the first three moves, when setting up your caravans, you do not draw replacement cards for those you lay out. Thus, when those turns are complete, you will have five cards in your hand.

Players take turns playing one card each. If you cannot or do not wish to play, you can discard a card from your hand. In any event, once a card is played or discarded, you draw a replacement from your deck. If desired, instead of playing or discarding a card, you can discard an entire caravan.

Play continues until "End game," below.

Cards and Their Effects

• Ace: Always a value of 1. Consider a number card except when a Joker is involved.
• 2 - 10: Face value.
• Jack: Removes the target card and all face cards attached to it from the board. Typically played offensively against the other player.
• Queen: Reverses the direction of the caravan. Can be used offensively and defensively.
  • Offensive example: reversing a descending caravan to ascending when the opponent is near enough the target (and at a high enough last number) that the direction switch prevents him from landing within the range. Rare, but very effective when you can pull it off.
  • Defensive example: You've been ascending or descending and either can't go farther (at a ten or an ace), or you need to reverse direction in order to land in the target range.
• King: Doubles the value of the target card. Again, can be used both offensively and defensively.
  • Offensive example: Double the value of a high-value card in your opponent's caravan when he's at the high end of the target range. Boom, now he's overloaded.
  • Defensive example: Double your own card (typically effective early-game) to get a leg up on the competition.
• Joker: This one has different impacts depending on the card you play it against. Often ends up doing "collateral" damage -- that is, damage to you as well as your opponent. Use them wisely.
  • Against an ace, removes all non-face cards of the same suit as the ace from the table, except the ace on which it's played.
  • Against numbered cards, removes all cards of that value from the table, except the card against which it's played.

End game:

The game is over when all three Caravans are successfully sold. When a caravan is between 21 and 26 (inclusive), it is considered sold. However, you can continue to pile weight on a sold caravan, and your opponent can continue to outbid you. Whichever player has the highest bid (without going over) on two out of the three Caravans wins. Ultimately, the goal is to get two out of three caravans as high as possible (preferably 26) before the opponent does, and to prevent the opponent from outbidding you by using offensive maneuvers against him.

Note that the comments refer to bugs regarding this behavior. I've not personally observed any bugs here; I've never personally seen the game end without three caravans being sold. However, not all three must be sold by the same player. For example, if we numbered our caravans 1 - 3, a game could end with one player having sold #s 1 and 2, and the other having sold #3. Whoever has sold at least two at the end of the game has won.

But wait — there's more

In case this wasn't quite clear/useful enough, there's an excellent explanation here.

Building a Deck

I'm not going to give many strategies on this, but just the basics. First off, as of the (what I assume are final) patches, cards you purchase or find seem to go in your deck straightaway. You will need to modify the deck you have in play before the game begins. (This is the part where you see all your cards in two rows on the screen.)

For your deck, you want to think about the odds of getting the card you need when you need it. Really large decks allow you to survive even the most aggressive AI, but often don't provide the attack cards you need to keep the opponent from winning while you build out your plan. Really small decks often provide a card you need, but have no longevity against an opponent who relentlessly hits you with jacks and kings.

Personally, I build what I call a Deck of Black Death:

• Exactly one of each Ace (heart, club, spade, diamond)
• At least 4 of the following (all clubs or spades): 2, 3, 7, 8
• At least 3 of the following (all clubs or spades): 9, 10
• At least 5 of the following (all clubs or spades): 4, 5, 6
• At least 4 of the following (I try for all black, but can be any color): King, Jack, Joker
• Exactly 3 Queens (again, I try for all black, but can be any color)

Why the emphasis on black? Because of Joker-on-Ace. In all my playings, I've never seen the AI play a Joker. Never. But I will use them very aggressively. And by keeping most of my deck contained in two suits, I know that I can always play a Joker on a red Ace, hurt the AI, and probably not hurt myself at all. (YMMV if you're playing with actual cards and actual people.)

The other reason I emphasize black is to increase the odds that I can switch direction without playing a Queen. All of my value cards are either spades or clubs, making it more likely that I will get a matching suit when I draw, or already have one in-hand.

Note that this is pretty flexible: "at least." The main thing is the general proportions -- don't go for too many high cards, because they reduce flexibility. By the same token, don't get too many low cards, because they delay your advancement. You need a lot of face cards, but you need them to be well-outnumbered by your value cards. The only inflexible bits are the Aces and Queens -- Aces because you only need one of each, Queens because they have very limited use, especially with limited suits.

I feel a lot has been left unsaid in the other answer and still felt very confused after reading it, so I've written up a summary in a way that makes sense to me.

The big picture

Caravan is played between two players. Although it's played with traditional playing cards, each player has their own deck, and what's more, you get to choose what cards are in your deck. In this way the game is more like Yu Gi Oh or Magic than a traditional card game. You can find cards all over the wastelands, and every time you start a game of Caravan, you choose what cards you bring into the game - this is your deck for the game. There are only two rules for what cards you can put in your deck: it must contain at least 30 cards, and you can't have two identical cards (same suit and rank) from the same casino.

The game basically simulates an auction. There are three "caravans" that you and your opponent are trying to buy, by outbidding eachother. Your cards are going to act as "money", and you'll "bid" by playing cards.

Look at the six piles of cards on the left. You can see that each pile has a name - Boneyard, The Hop, etc, but the names are just flavor and don't matter. The number next to the names of the pile is the sum of the values of the cards in that pile (eg. the bottom right pile has a 26 because 26 = 6 + 4 + 10 + 5 + 1, and the Ace counts as a 1). The bottom three piles are "yours", the top three piles are "theirs". Each of your three piles represents the amounts of money you've bid so far for each of the three caravans, and the piles opposite them represent your opponent's bid for the same caravan.

Each player has a hand of five cards. On your turn, you bid "money" on a caravan by adding a card to one of your three piles. Once you reach 21, that caravan is "sold" to you - but your opponent can take it by bidding even higher! However, if either one of you bids more than 26, then that's a bust, and you don't get that Caravan anymore. Since it's also possible to remove cards from either your or your opponent's piles (more on that later), the caravans can change hands several times over the course of the game, with you and your opponent outbidding eachother, removing cards from your piles, and bidding again. The game ends when all three piles are simultaneously sold (someone has bid between 21 and 26, inclusive), and the winner is whoever has the most of them (since there's three caravans, there can't be a draw, of course).

Example 1. Suppose the piles look like this:

12 26 09

22 25 21

Then you the first and third caravans are "sold" to you, but the middle one is sold to your opponent, because even though you're both in the 21-26 range, they bid more. The game is over, since every caravan has been sold to someone, and you win, since two out of three were sold to you.

.

Example 2.

14 15 19

26 17 07

Here the game isn't over yet, since nobody has been able to buy caravans two and three yet. Now say you add a 5 card to your middle pile

14 15 19

26 22 07

Now you have caravan two, but the game still isn't over because the third caravan is still up for grabs. Now your opponent adds a 10 card to their middle pile.

14 25 19

26 22 07

Your opponent outbid you on the second caravan! It's now theirs unless you outbid them back. But let's say you just play a 10 card on your third pile and then your opponent plays a 2 card on their third pile.

14 25 21

26 22 17

Now the game is over, because all three caravans have been sold - the first to you, and the second and third to the opponent. You lose.

How to actually play

The first screen you see when you start a game is the betting screen - negotiating the stakes with your opponent. The game can't start until each of you have agreed on an amount, so just hit A to automatically match your opponent's bet and start the game. This screen is pretty self-explanatory.

Next comes the bizarrely unintuitive deck-building screen. The bottom row of cards are all of the cards you've collected in your travels. The top row of cards is... the same thing, but flipped around (cards that are face up on the bottom appear face down up top and vis versa). You're choosing which cards to bring with you into the game (remember, you have to have at least 30) The cards are that face up on the top row are the ones you're choosing to bring with you. The only rule other than needing at least 30 is that you can't have two cards of the same suit and rank from the same casino. A very, uh... creative interface for something as simple as choosing cards from a deck.

Now you get to the game. You're dealt 8 cards. Choose three cards to place as the foundations for your three bidding piles. You now have five cards, and the game proper starts.

On your turn, you can either:

1. Play a card from your hand (add it to a pile), and draw a new one from your deck.
2. Discard a card from your hand and get a new one from the deck.
3. Remove one of your three bidding piles from the table and start a new one.

Now, there are two kinds of cards: the number cards (including the Ace, which counts as 1), and the face cards. The number cards are, as mentioned above basically "money" that you bid with. The face cards are completely different: they aren't used to bid, they have special powers. Whereas number cards can only be added to the top of a bidding pile (and only one of your piles), the face cards are "attached" to any card that's already in a pile, and they trigger special powers (which I won't go into), and you can do this even to your opponent's cards.

If you play a face card, then pick any card to attach it to and away you go. If you play a number card, though, there are some rules. You can add a number card to a bidding pile under either of two conditions:

1. The number card has the same suit as the last number card added to that pile.
2. The number card is going "in the same direction" as the pile. That is, each pile is either ascending or descending. If a pile goes 5-6-8, then the next number card can't be a 4, it has to be a 9 or a 10. Whether a pile is ascending or descending is determined as soon as you place the second card in it.

Remember: either of these conditions have to be met, not necessarily both.