FIND BLACK'S BEST CONTINUATION

Black to Move

Check your solution on Apronus. 

THE GAME LASTED ONLY 13 MOVES

I had black pieces. We played on the platform Chess-Mail. 

The game was finished on the 13th move with the Greco's mate.

[Event "Match"]

[Site "www.chess-mail.com"]

[Date "2024.01.12"]

[Round "1"]

[White "Geodad5"]

[Black "Nanomaster"]

[Result "0-1"]

[WhiteELO "2030"]

[BlackELO "2300"]

[Termination "6"]

     1.      e4            e5      

     2.     Nf3           Nc6      

     3.      d4          exd4      

     4.    Nxd4           Bc5      

     5.     Nb3           Bb6      

     6.     Bd3            d6      

     7.     O-O           Qh4      

     8.     Nc3           Nf6      

     9.     Na4           Ng4      

    10.      h3          Bxf2+     

    11.     Kh1           Qg3      

    12.     Bf4          Qxf4      

    13.    hxg4           Qh6+     

            0-1

The move 9 Na4?? was a grave mistake. White wanted to eliminate Black's bishop b6, which was attacking the pawn f2. 

The correct move was 9 Qd2! with equal play.

In the game, after 9 Na4?? Ng4! the pawns f2 and h2 were both under attack. White had no time to capture on b6, and White's both knights were on the wrong flank.

9 Na4?? Ng4!

The result was a classical Greco's mate:

Greco's mate

The pattern of the combination that starts with 9...Ng4 is standard.

THE GAME LASTED ONLY 10 MOVES

Gegonz - Nanomaster 
Chess-mail, 2023-2024

I had black pieces.

It is not a fork

If Black takes the knight a5, then White takes the knight d2.

If 10...Bxa5, then 11 Kxd2.

The position after 10...Ne4!

After the move 10...Ne4!, two White's pieces are attacked at once.

However, this is not a fork because two Black's pieces are involved in the combination.

Such a combinatorial motif seems common in chess but has not received due attention. Such a tactical motif does not even have a name (or well-known name).

Yes, it is zwischenzug.

However, here, it is a particular kind of zwischenzug. Zwischenzug is used here to defend against the opponent's threat and create a new threat - so that, in sum, two threats against the opponent will appear on the chessboard.

And no, it is not the roentgen motif.

In the case of the roentgen motif, two opponent's pieces are suddenly attacked after one move, while the attacker's two pieces are involved. However, in our example, one of the opponent's pieces was under attack from the very beginning.

Thus, it is neither a fork nor a roentgen. And it is too general to say that it is a zwischenzug merely. But after one move, two opponent's pieces are simultaneously under attack, similarly to a fork or a roentgen.

CHECKMATE IN 7 MOVES

White to checkmate in 7 moves

You can check your solution on Apronus.