Return to the Strategy of... Battle Line

Dear all,

Since my original post on the strategy of Battle Line, many such games have come and gone. Greater exposure has inspired  many further thoughts, which I am now minded to share with you all. This article has been rather difficult to lay out, as the concepts at work tend to run into one another. I shall separate it into hand management, where to place, and when to place, and hope that this structure proves helpful. Again, the tactics cards will not be discussed here... though I have had thoughts on that subject as well...

Thinking about the contents of your hand

As discussed in the original article, one should always start by playing for a straight flush (since they can be easily converted to a straight or a flush), and play a higher-value (preferably centred around an 8) against a lower-value, or (if not possible) a lower-value (preferably centred around a 3) against a higher-value straight flush. From these considerations, the following definitions of cards in hand at the beginning of the game can be thought of in two ways:

High in value: higher cards beat lower cards with the same formation. That's easy to grasp. Slightly more subtle is the concept of...

High in probability: the chances of a successful formation being completed. At this beginning of the game, this refers to the likelihood that a straight flush is possible. Two cards of the same suit with adjacent values (henceforth a "double") are high in probability; provided that neither is a 1 or a 10, there are two cards which can complete the straight flush. By comparison, a "split" (i.e. two cards with a number in between, such as 7 and 9) require a single specific card to complete the straight flush; in short, there are fewer ways of completing the formation. (Note that this is also the reason why, considering single cards, an 8 is better than a 9; there are more ways to complete the formation around an 8, as it has three potential straight flush formations, whereas a 9 can only be in two formations.) At the beginning of the game, a double has a better-than-average chance of completing; a split has slightly less than a 50/50 chance (as cards still in the deck will be evenly split, but there are those in the opponent's hand, as well as those which will never be picked up, which reduces the odds of acquiring a specific card).

These considerations are crucial when deciding what to play in a certain position (given the priorities below). If one wishes to win a position where the opponent has already placed, it is generally best to play something higher in value (if possible); however, depending on the game state, you may decide you have better odds of success by playing something low in value but high in probability (i.e. if, given what is in your hand and already played, you think it is unlikely the opponent can complete their higher-value formation). By contrast, when playing to an open position, high in probability is generally better than higher in value.

The junk pile: At the beginning of the game, any card has the potential to form a straight flush. As the game proceeds, this will no longer be the case. Those cards which are no longer valuable for completing straight flushes should be considered separately - I call it the "junk pile", though that is rather glib, as these cards actually play essential roles. Specifically, they are the cards that will be used to fill out straights and flushes where the straight flush has failed, as well as collect three-of-a-kind to defeat the opponent's failed straight flushes. Thus the "junk pile" is really the second string, where unbroken straight flush cards as the first string. Try to keep track of which cards can be used to complete which formations!

Trash: finally, we have cards which cannot be used for any purpose. In practice, these won't accrue until the late stages of the game - until you have played cards to every position, and as least some of these are closed, most cards will still have potential (in the junk pile at worst). Cards only become useless trash when they cannot contribute to any hypothetical position. Trash cards have a single potential purpose - to demonstrate, where possible, that the opponent's formation cannot be completed (and therefore that you have won the position). Generally, try to keep them in hand until the opponent has lost the position, and then reveal by playing on a position with the lowest possible priority (you'll lose that position, so try to hold back until you can win essential positions by revealing the opponent's failure).

Placement priority

... that is, which are priorities to win (and hence positions where you will want to play high probability and value), and those which are lower priorities. These considerations mainly come into play when considering which open position to begin strongly, but may be relevant where a single card may be used in more than one active formation, or where timing is important. In practice, this will usually be a judgement call, and depends on the current game state, but I would generally prioritise positions in the following order:

1. Positions which win you the game (usually by breakthrough). This much is self-evident.
2. Positions which prevent the opponent winning, again usually by breakthrough. If an opponent has won two adjacent positions, you must prioritise winning one of the next adjacent positions to prevent their success.
3. Positions which will build towards a breakthrough. If you are strong in one position, try for the adjacent positions.
4. Positions which will impede your opponent's breakthrough; that is, play strong to an adjacent position, particularly if it fills the gap between positions in which your opponent is already strong. (At this point in the list, game state becomes increasingly important in choosing priority... depending on the board, your hand, and deductions about your opponent's hand, it may make sense to increase the priority of this).
5. Anything from here is a judgement call between playing against positions your opponent has begun, or opening strongly at positions where you may build towards a breakthrough.

When to place

Advice often given to beginners is that Battle Line has a second-player advantage, as the second player can choose the most relevant card to play after seeing what the first play has placed. I do not necessarily agree with this; sometimes, I believe it is better to choose to play to an open position, even when there is the option to play responsively. Of course, if you are the first player, you may have little choice; however, even when you are the second player, you might want to start a new position rather than responding to the first player. This is because, if you are lucky enough to have a starting hand which is strong (particularly in probability), it may be smart to establish a potential breakthrough position at the beginning. By the same token, if you only ever play in response to the opponent's starting card, you may end up giving away a breakthrough (i.e. by playing three lower-in-value cards where the opponent succeeds in delivering their higher-value formation). Thus, deciding whether to open a new position or play in response to the opponent is a judgement call based on your own hand and the opponent's placings. All I can offer as guidance are the hand considerations and placement priorities above.