First Principles

In general, we want all of our strategies to flow from some basic principles. That way, new players can just learn the first principles, and then use logic and reasoning to find out the resulting strategy that their teammate is intending. However, there are a few wrinkles with this:

  1. Some of our strategies are arbitrary and do not flow from the first principles. So take the phrase "First Principles" with a grain of salt.
  2. Since the principles are a little abstract, they are more useful as a reference than as an actual guide on how to play Hanabi with our group - this is what the beginner's guide is for.

1. Chop Principle#

  • The "chop" is the right-most (oldest) unclued card.
  • When a player needs to discard and has no known safe discards, they should discard the chop card.

2. Minimum Clue Value Principle#

  • A given clue must either:
    • indicate sufficient information for one or more previously unclued cards to be played (as a Play Clue)
    • prevent the possible discard of one or more previously unclued cards that need to be saved (as a Save Clue)

3. Save Principle#

  • Cards that meet the following criteria must not be discarded:
    • only one copy remains (e.g. 5's or unplayed cards in the discard pile)
    • it is a 2 and not visible elsewhere in players' hands
    • it is currently playable and not visible elsewhere in players' hands
  • When a card that needs to be saved is at immediate risk of being discarded, it must be indicated with a Save Clue (or a Play Clue if it happens to be playable).
  • If a player receives a clue that could be either a Save Clue or a Play Clue, they must consider both possibilities. Specifically, this means that the player must hold on to the card until they know for sure.

4. Good Touch Principle#

  • A safe discard is defined as:
    • a copy of a card that has already been played
    • a copy of a card that is in someone's hand and has been clued
  • Safe discards should not be clued (unless there's an important reason to).
  • Players should generally assume that any clued card in their hand will eventually be played.

5. Play Order Principle#

  • When a Play Clue touches multiple cards, if it includes the chop, it's focused on the chop. (This is referred to as the Chop-Focus convention.)
  • Otherwise, the clue is focused on the newest (e.g. left-most) of cards that did not have a clue "on" them already.
  • The non-focused cards may or may not be playable.

6. Left-Most Playable Principle#

  • When a player is expected to play a card (or know a card is playable) in a situation not covered by the Play Order Principle, the card to be played is the left-most of the various cards that are most likely to be it.

7. Information Lock Principle#

  • What is indicated by a clue is determined by the known information at the time the clue is given. Subsequent clues may build upon that information, but do not override it unless a direct conflict is evident.

8. Lie Principle#

  • Normally, players try to make their clues as clear as possible and convey the exact identity of a card.
  • Rarely, players can use clues to trick other players into thinking that they have cards that they really don't.
  • If this untruth resolves immediately (e.g. the very next turn), it is called a Fib. For intermediate and advanced players, Fibs are legal and expected.
  • If this untruth does not resolve immediately, it is called a Lie. Lies are illegal. Players should never assume that they are Lied to.

9. High Value Principle#

  • The highest value clue is expected. If a clue is given, it should be interpreted to be the highest value move available to that player.
  • In other words, you can draw many important conclusions from the fact that a player did not do some other (potentially higher-value) move.