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.