# Timo's 2p Conventions

These conventions were developed by @timotree3 in May 2021 in collaboration with @indego, @Lel0uch-H, @melwen, MarkusKahlsen, and HelanaAshryvr as an alternative to [IAMJEFF's Score Hunting Guide][]. Some big differences include:
- Safer playstyle, e.g. [save stalls](#Permission-to-discard--Save-Stalls)
- [More powerful Focus Inversion and Self-Color Bluffs](#Play-clue-timing)
- [A powerful convention for unlocking a locked partner](#Playing-cards-into-a-locked-hand)

[IAMJEFF's Score Hunting Guide]: https://github.com/iamwhoiamhahaha/hanabi/blob/master/2-player/Score_Hunting_Guide.md

These are still my personal favorite 2p conventions with a discard-oldest assumption, but now that [Sieve][] and [Referential Sieve][] have been invented, I recommend those for 2p.

[Sieve]: https://hackmd.io/@sjdrodge/S1pRVuxsu
[Referential Sieve]: https://hackmd.io/@timotree3/Byn3cjSZK

## Basic conventions

The following H-Group conventions are turned on:

- Chop-Focus
- 2 Saves
- 5 Saves
- Critical saves with color
- Critical saves with rank
- 5 Chop Move
- 1's Order Chop Move
- Trash Order Chop Move
- Trash Chop Move
- Misplay Chop Move (play cluing trash)
- Tempo Clue Chop Move (modified)
- Scream Discard Chop Move (modified)
- Finesse
- 3 Bluff
- 5 Pull
- Double Ignition
- Elimination Notes
- Priority Prompt
- Focus Inversion
- Self-Color Bluff
- Trash Push
- Pink Promise

The following widely known 2-player conventions are turned on:

- Priority Elimination Notes
- Misplay Double Chop Move
- Selfish Color Chop Move
- Flush Clue
- Early Fix Clue Chop Move
- Risk of Duplication Chop Move
- Implied Color Saves
- Fake Saves with rank
- Fake Saves with color
- Sarcastic discarding playables promises position and must be done ASAP

## Play clue timing

Give 1-for-1 play clues ASAP (even before playing a card) with four exceptions:
1. You can instead play a card that potentially duplicates it.
2. You can instead give a save clue that unlocks a better play clue on the card. (Either because the better clue would currently be chop focus or you see a chop focus 2-for-1 after the save)
3. You are forcing a discard that triggers Elimination Notes.
4. You have a safe action and there are 2 or fewer clues.
- (does not include discarding a card that might be a connecting card)

Give 2+ -for-1 play clues ASAP with the only exception being that you can instead play a card that potentially duplicates it.

If a 1-for-1 play clue is given too early (meaning that either condition 1 or 4 is known to be true) it signals a chop move.

If a play clue is given too late, the card is known not to be directly playable and it signals Focus Inversion, a Trash Chop Move, or a Finesse Position blind-play.

## Tempo clues

Tempo clues are clues which get one or more already saved cards to play, without touching a new card.

Tempo clues touching two or more cards only promise one playable card. If it is not obvious which card is playable, assume rightmost on color clues and leftmost on rank clues.

Alice is required to give a tempo clue before discarding if there are 3 or more clues and Alice's discard could be a useful card of the same suit.

If a tempo clue is given that is not immediately required, it signals a chop move.

## Permission to discard / Save Stalls

The main way that we save multiple cards in a row is by bombing chop. We do not bomb or discard cards that could be critical unless the clue count is very low.

A card has permission to discard if
1. your partner has discarded while it was on chop and a clue token was available
2. or you have taken a turn while it was on chop, you didn't have any plays, and you weren't expected to save stall

You are expected to save stall if there are two or more clues, you have just received a save clue, there was no chance to give that save clue earlier, and your partner had no safe way to chop move more cards than were just saved.

As an exception, you are not expected to save stall if your partner could have bombed chop and either the save clue given was low value like 4 or 5 or there are 5 or fewer clues.

## Stall clues

Allowable stall clues are:

- Any 5 clue.
- Any useful rank clue that is not focused on freshly drawn slot 1.
- Any clue that only touches already saved cards.
- Any clue that is focused on a card that is potentially useful and cannot be directly playable.
- Any potential save on chop.
- Some clues that give known trash, depending on the variant.

## Self-Prompts

A Tempo Clue Prompt is when you reclue an already clued card to prompt both that card and another clued card. If the played cards lead into criticals that would be saved anyway, this signals a chop move. Otherwise, these should be given ASAP (even before playing a card). If the tempo clue is not given ASAP, then it turns into a bluff.

If a color clue is given on a new card that is known not to be directly playable, and there is an already clued card of the same color, this signals a prompt on the leftmost such card, instead of a bluff. If the prompt is not given ASAP, then it turns into a bluff. (Question: What about pink/brown/muddy suits? Should it just promise tempo on one card?)

Rank clues on new cards that are known unplayable are generally assumed to be bluffs instead of prompts, with four exceptions:
- The focused card is on slot 1, so finesse position is a bit stale.
- The rank clued is 5 and there is a color clued card that can be a playable 4 of the same suit, so it is known to be the 4 by good touch.
- In rainbow variants this is still allowed and prompts the leftmost such card.
- Must be given ASAP to avoid turning into a bluff.
- The rank clued is 4 and there is a color clued card that can be a playable 3 of the same suit, so it is likely to be the 3 by good touch.
- Prompts the leftmost such card
- Must be given ASAP to avoid turning into a bluff.
- I forgot the fourth

## Anxiety

When you are locked with 0 clues you are usually expected to play a card. If your slot 1 is freshly drawn, slot 1 takes precedence.

In other anxiety situations, we use context and negative information to determine which card is most likely to be playable, breaking ties with leftmost. If your partner declines to put you in anxiety by generating a clue, then you can mark the card you would've played as known unplayable and use that fact in future anxiety situations.

## Playing cards into a locked hand

If your partner has a locked hand, it is often better to discard than play a card, especially if that card does not lead into their hand. Therefore when you're locked and your partner is allowed to discard but voluntarily plays a card, it acts as a priority signal and prompts you to play the connecting card from the most likely slot. If this signal is delayed, it shifts slots.

If a locked player has a card that is far from being played, the number of stall clues required to play that card is equal to the card's distance from being playable. For example, if the red 1 is played, playing red 2 and red 3 requires two stalls, meaning that if the clue count is less than two, red 4 cannot be played.

- If you have known trash, you are expected to discard before playing, and playing promises that it unlocks your partner.
- If your chop can be useful, count how many stalls are required in order to play each of your partner's cards, if the clue lost by playing results in one of your partner's cards becoming impossible to play, then you are expected to discard.
- If your chop can be useful and there are enough clues even after playing, then you are expected to play, even if it does not unlock your partner.

If you have two or more spare slots, then a hard burn clue implies your chop is trash. (If you have only one spare slot, a hard burn clue implies your chop is not critical but not necessarily trash, because your partner may be waiting to see your next draw before saving a non-critical.)

If the locked player does not know how far away from playable their cards are, then they may not be able to predict plays, and thus they should save the most important critical card first.

## Inverted Elimination Clues
After writing elimination notes for a playable card, a clue that leaves only one slot available for the second copy to be is considered an Inverted Elimination Clue and does not promise anything other than good touch. (How does this interact with pink promise?)

## Selfish Clues

If you have a known play of a certain color and you give a clue of the same color, that is considered a selfish color clue.

- A selfish color clue on chop means nothing extra. (What if the player has known trash or a play?)
- A selfish color clue touching a single card chop moves ALL of the cards to the right.
- Exception: Players are allowed to lock in the play clue if the card that would be chop moved has permission to discard, the player does not have a known play, and after a discard it will look like a save clue.
- A selfish color clue touching two or more cards that after a discard will be chop-focus is leftmost focus and means nothing else extra.
- A selfish color clue touching two or more cards that after a discard will still be leftmost focus is rightmost focus.

Selfish Color Bluffs?

## Flush Clue Exceptions

As an exception to Flush Clue, we are allowed to give color saves on freshly drawn slot 1 if it unlocks you by giving a play or known trash.

In a situation where the player knows that one of their cards is trash and the other is useful, filling in either card would unlock them. So ideally we designate a particular card to fill in (as either a save clue or early fix clue chop move) to allow for more efficient play clues.

Assuming they're both clued with rank and it's not a white variant, we agree to fill in the leftmost card in question if we intend a save/CM, and otherwise slot 1 is playable. Example: https://hanab.live/replay/543395#16 is yellow a save? Is green an early fix cm? Due to this convention, yellow is a save and green is an SCB.

## 7 Clue Stalls

After an 8 clue stall, the player with 7 clues is allowed to give a stall clue in return. (But is not obligated to.)

## Trash Push Assumption

In the endgame, it is often a good idea to trash push playable cards instead of giving a direct play clue. If a direct play clue is given and a trash push was known to be available, the focused card should be considered not directly playable, and therefore either finesse position or an already clued card should play instead.

This does not apply if the clued player already had a play (because a direct play clue allows for priority) or if the trash push would allow the connecting card to be discarded.

## Save clue timing

If you can play a card and leave your partner without permission to discard/bomb chop, then it's too early to give a save clue. If you give a save clue too early, it means that either the card is playable or you need to give multiple save clues in a row.

If the card is known not to be directly playable, the early save triggers a chop move. If the card can be playable, then the player should wait and see whether a follow-up save is given on the next turn. If a follow-up save is not given, then it turns into a play clue.

Question: How does clue count tie in? What if your spending the last clue to give a save? Is it too still early even though your partner might waste that clue?
Question: Are there some cases where we should be allowed to discard before giving a save clue?

## 5 Fill-In Doubles

It does not gain tempo to fill in an already saved 5 as a 5. Therefore when a 5 fill-in is given and it doesn't disambiguate that card from other similar looking cards in the same hand, it is treated the same as a No-New Information Double and calls for two blind plays unless the first card that plays is easily blocked.