Hanabi - how to read behaviour clues...

The most important and the most hard part of this logical game is, ofc, logic. I sometimes see masters that doesn't believe their coplayers make rational moves. (Or, worst, I've seen masters that were doing really irrational moves, choosing the worst possible options.) It didn't matter much if deck is kind for you...

But if it isn't?

Understanding behaviour of the other player is mostly useful in 2p (and 3p). And as behaviour is situational, there is nothing like standard procedure, 'convention'. OFC some experience will tell you the most probable reason for any weird behaviour, but you have to think through every possibility every time. Put yourself in the other player's situation. In what situations would you give that kind of clue?

If I was about to give examples of all possible situations, it would be post without end, so let's focus on 'basics'. And on 2p. If you can play 2p really well, you can play all.

Situation 1 (typical):
There is no clue or 1 clue. You see your coplayer know about his playable card, and yet he discards. What can it mean?
If there is no clues, he probably shows you to not discard last card. Not necessarly forcing to discard the next - but that depends on the context. If there was no earlier odd behaviour - he didn't care about your chop, then you used last clue to clue him about playable, and he discards - you can usually assume it's the card to play after he plays (and that your next chop is safe discard). On the other hand, if he discarded and you clued him sth to play, and he discards again, it means your chop started to matter, like... it was the twin card of the one he just discarded?
What should you do with it? Well, depends. From the deck and from your own imagination, and risk assessment. Some players just move their chop to the next position. Some discard firstly marked non-unique card, because it's the best way to know they are not discarding anything crucial (as second chop could be unique too!). Sometimes they just clue until the other player gest a card that give the cluer a play.



Example 1: (Table #24114591 on BGA)

Last clue to me before 1 was green, what tells me that my last 4 cards aren't green (that's important for later). Then I was clued 1. Ok, so either he has more than 1 crucial card to save at once, either want to save more than 1 card - unique and possible play. We'll see.
I clue (empty clue), he discards, draws 5w, I clue white, he plays & draws 3b. I clue blue. He plays 3b. I discard 1. Then he clues me yellow on newest AND on two cards that I have during 1 clue. So when he clued 1, my hand looked like this: Xy 1 Xy X X.

I play newest - 3y in play. He knows he can play the his 4 (red 4), and yet he discards.  I clued his 4bs, he discarded one of them, to ensure me something is wrong. Ok, so 1 wasn't greedy, but attempt to save. So... what does he want to save?
By quick look at the discard and the history, it starts to be obvious that it isn't any needed 4 nor 3 (it's not yellow, and all the rest 4s he has), so... 5. More than one 5, because if my second-to-chop was safe discard, instead of 1 would be just 5 on chop. So I have two 5s - non green - non yellow - so red and blue. Cool. What about yellow cards?

I assume people clue cards that are needed somehow - now or later, or when it would be easy to show they are not useful or when I didn't care about the bomb. Due to situation I was not sure he would play blue before I clue him, and blue clue gave him a lot of info.

So I was clued yellow cards. Yellow cards that are important are 5m (playable - I don't have it, as from two yellows that were left, second card is solid yellow, while first would be clued to play earlier), 5y and 4y. Great, so I have playable 4y. Can I know where is it?

Yes, I can!
Why would gorosei clue 1 if he could just clue 5s at my chop, I would discard 1 and then he would save 4? Nonsense, isn't it? So... So my cards can't be in the order "x 4y 5y 5 5". As for 5th card (x), I know nothing - it may be playable or discardable - if I really didn't know what to do, I would play it, possibly bombing, but in some situations it could be safe option.

Instead, I play 4y. My reasoning was correct. When gorosei clued 1, my hand was [5y 1 4y 5 5]. After playing 4y I know I can safely play other yellow card; anyway gorosei clues my 5s to ensure about them - and to let me know that I don't have any other 5. I play, he plays, I wait, and when both 4r and 4b are on the table I play 5.

Situation 2:
Other player has a play - card marked but without full info, and by the timing he can't know it's a play - so he discards, as you expect. You discard too. Either you can't clue his playable without marking trash cards, or you have another reason to not do it, doesn't matter. And... after your discard, the other player plays his play. Why?
Well, apparently he noticed it has to be a play. So - your newest card is the card he suspected as his card... Like, when one of 3b is on the discard (and all other 3s are playable) and you clued 3r by 3 on chop. The other player can't know it's play - until you drew the real 3b - and when he plays, it shows you exactly where do you have the interesting card.
Similar situation can be found when a player A clues save on B or C, but that save info makes that player play another marked card. Example: There is 2y on the table. Player A has 5y on his hand. C has solid yellow card on his hand. B clues C about two 4s on chop (there are some 4s on the discard). C can't know if either 4 is yellow, BUT save clue made him know about a play: 3y (unless the gameflow made him suspect unplayable - it can happen when you have to clue card that you can have on your own, but not cluing it would made game a lot worse if you don't have the card). In this case, despite that after 3y play A knows to have 5y, he can't know where.
Generally: unexpected plays give info.

Example 2: (Table #27020683* on BGA)
Around beginning, I clued two 4s (one to play: 4y, and the other 4m) on qpenguin. Some 4s landed on the discard pile including unplayable 4w. 4m was waiting on the other player's hand, no color clue was done in the meantime, until white clue that marked playable 3m and 5w,4m.

3m was played and the other 4m was drawn. I didn't feel like it was needed to clue it right away. I clued a null clue and partner discarded. I played my earlier marked play (5g). And then 4m was played...

And I knew my newest card is 4w. Why otherwise sudden change of the knowledge? Discard while having a play could mean sometimes to avoid discard chop, but only if the other player is sure that you know about your play. And with my point of view, I couldn't assume he knows its 4m, unless he does see 4w. Which a moment ago he didn't.

*During this game I made stupid mistake - overlooked 2w and let it be discarded with no reason. :(



I wanted to make one more example, but specially for Isdariel, publication now. ;)