UnicornFork · Your AI chess coach

AI chess coach · Backed by Stockfish

Understand the _why_ behind every move.

**Stockfish finds the best move. UnicornFork explains it.** Ask about any position in plain language and get answers you can see on the board.

Meet UnicornFork

Stockfish's moves, explained in 30 seconds.

See it in action

Ask about a move. See the answer on the board.

Morphy's Opera Game, Paris 1858. Hover or click the moves in the chat to see them on the board, or step through the game.

What's the best move here?

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**16.Qb8+!!**, a queen sacrifice that mates in two: 16.Qb8+Nxb8 17.Rd8#.

Why it works:

- **White has no time to lose.** Black threatens ...Qxb3, trading queens, and is a point up in material.

- **The knight on d7 is the only defender.** It blocks the d-file and guards b8. Taking the queen pulls it off the file, and the rook on d1 comes to d8.

- **The king is boxed in.** The bishop on g5 covers e7 and protects d8, while Black's own bishop on f8 and pawn on f7 take the other squares.

The natural moves are much weaker. 16.Qc3 keeps a winning attack (+3.5) but takes far longer. 16.Qb5, pinning the knight, even lets Black escape: after 16...Be7 17.Bxe7 Kxe7 White has nothing better than checks, and it's a draw.

| Move | Eval | | Engine line | | --- | --- | --- | --- | | 16.Qb8+ | #1 | engine best | 16...Nxb8 17.Rd8# | | 16.Qc3 | +3.31 | mistake | 16...f6 17.Qc8+Ke7 18.Be3 g5 19.Qc7 Ke8 | | 16.Qb5 | +0.00 | blunder | 16...Be7 17.Bxe7 Kxe7 18.Qb4+Ke8 19.Qb7 Ke7 |

Why does Black have to take the queen?

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Because it's the only legal move. The queen on b8 gives check along the eighth rank, and there's no other way out:

- **The king can't move.** The red squares are the ones next to it that White attacks: the queen covers d8, the bishop on g5 covers e7, and the rook on d1 hits the knight on d7. Black's own bishop and pawn fill f8 and f7.

- **Nothing can block.** The squares in between are c8 and d8, and no black piece reaches either.

So 16...Nxb8 is forced, and it takes the knight off the d-file: 17.Rd8# follows. The rook checks from d8, the bishop protects it and still covers e7.

Notice Black's rook on h8 and bishop on f8: they haven't moved all game. That's why the king had no room and no defenders when White's pieces arrived.

1 2 3 4 5 6 7 8 a b c d e f g h

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1.e4 e5 2.Nf3 d6 3.d4 Bg4 4.dxe5 Bxf3 5.Qxf3 dxe5 6.Bc4 Nf6 7.Qb3 Qe7 8.Nc3 c6 9.Bg5 b5 10.Nxb5 cxb5 11.Bxb5+Nbd7 12.O-O-O Rd8 13.Rxd7 Rxd7 14.Rd1 Qe6 15.Bxd7+Nxd7 16.Qb8+Nxb8 17.Rd8#

Mistake Blunder

Coaching prompts

Make the coach your own.

**A prompt decides how the coach works for you:** how deep it goes, how much jargon it uses, how long its answers are. Here's the question from the game above with each built-in prompt.

What's the best move here? Morphy's Opera Game, after 15...Nxd7

**16.Qb8+!!** wins on the spot: a queen sacrifice that mates in two, 16.Qb8+ Nxb8 17.Rd8#.

- **The knight on d7 is Black's only defender.** It blocks the d-file and is the only piece that can take on b8. Taking the queen pulls it off the file, and the rook comes to d8.

- **The king has nowhere to go.** The bishop on g5 covers e7 and protects d8, while Black's own bishop on f8 and pawn on f7 take the other squares.

Other moves give Black time. 16.Qb5, pinning the knight, even throws the win away: after 16...Be7 17.Bxe7 Kxe7 the bishop on g5 is gone, and it's a draw.

**White has something crushing here. Can you find it yourself?**

- Look at Black's knight on d7. What is it doing for Black right now? It has more than one job.

- Now look at White's rook on the d-file. Which square would it love to reach, if only the knight weren't in the way?

- Is there a check that forces the knight to leave its post, even if it costs you something big?

Give it a try: which move would you play?

**White can win right away by giving up the queen!**

- **16.Qb8+** puts Black's king in check. The only way out is to take the queen with the knight: 16...Nxb8.

- But that knight was standing in the way of White's rook on the d-file (the column the rook is on). Now **17.Rd8** is checkmate: the rook attacks the king, the bishop on g5 protects the rook, and the king has no square to run to.

This trick is called a **deflection**: you lure a defender away from the job it was doing. When one enemy piece guards something important all on its own, look for a way to pull it away.

None of them quite right for you? Copy one and change it, write your own from scratch, or pick one other players share.