The endgame in hanabi is complicated. This post is not a guide about endgame strategies, but instead a list of puzzles with very complicated solutions. I think even the best hanabi players will have a hard time with these.
For every puzzle I will link to the board if I have it, but I will also give all the essential information needed for the puzzle. In some puzzles, it depends on the deck what the best move is, but since you don't know the deck, your goal is to maximize the expected score. Describe for each puzzle what the best move is, and any later decisions which are not trivial.
Puzzle 1: #37853032, florrat's turn with 4 cards in deck.
2 players, 4 cards in deck, 3 clues. To play: G3 and up, Y5, W5. 1 copy of G3 and G4 are in discard.
Your hand has only useless cards. Partner's hand: R3 R1 B2 G5 W5, the G5 and W5 are fully clued.
Puzzle 2: (no seed)
2 players, 3 cards in deck, 1 clue. To play: M4 and up, R5, Y5. 1 copy of M4 is in discard.
Your hand: nothing clued, recently you were incredibly low on clues, so you might have M4 in hand.
Partner's hand: B1 Y5 R5 B1 M5. The M5 is fully clued, no other card is clued
Puzzle 3: #35314150, gamblingoof's turn with 3 cards in deck.
2 players, 3 cards in deck, 3 clues. To play Y5, M3 and up. Multicolor cards in discard: M3, M1, M2.
Your hand: 2 of them are marked as multicolor, but without number information, so one of them might be useless. They were first clued as part of a play clue on the Y3 in the endgame. They are not M3s, because partner would have told you that.
Partner's hand: W3 R3 R2 Y2 Y5 M4 with the Y5 and M4 fully clued.
For every puzzle I will link to the board if I have it, but I will also give all the essential information needed for the puzzle. In some puzzles, it depends on the deck what the best move is, but since you don't know the deck, your goal is to maximize the expected score. Describe for each puzzle what the best move is, and any later decisions which are not trivial.
Puzzle 1: #37853032, florrat's turn with 4 cards in deck.
2 players, 4 cards in deck, 3 clues. To play: G3 and up, Y5, W5. 1 copy of G3 and G4 are in discard.
Your hand has only useless cards. Partner's hand: R3 R1 B2 G5 W5, the G5 and W5 are fully clued.
Puzzle 2: (no seed)
2 players, 3 cards in deck, 1 clue. To play: M4 and up, R5, Y5. 1 copy of M4 is in discard.
Your hand: nothing clued, recently you were incredibly low on clues, so you might have M4 in hand.
Partner's hand: B1 Y5 R5 B1 M5. The M5 is fully clued, no other card is clued
Puzzle 3: #35314150, gamblingoof's turn with 3 cards in deck.
2 players, 3 cards in deck, 3 clues. To play Y5, M3 and up. Multicolor cards in discard: M3, M1, M2.
Your hand: 2 of them are marked as multicolor, but without number information, so one of them might be useless. They were first clued as part of a play clue on the Y3 in the endgame. They are not M3s, because partner would have told you that.
Partner's hand: W3 R3 R2 Y2 Y5 M4 with the Y5 and M4 fully clued.