An in-between move can radically alter the tactics in a position.
Tarvo Seeman White
Vilka Sipila Black
Baku 2016
Reti Opening A07
1 ♘f3 d5 2 g3 c6 3 ♗g2 ♗g4 4 c4 e6 5 0-0 ♘d7 6 d3 ♘gf6 7 ♗e3 dxc4 8 dxc4 ♗c5 9 ♗xc5 ♘xc5 10 ♘c3
Black now declines an equal endgame (10...♕xd1 11 ♖fxd1 ♗xf3 and ...♔e7/...♖hd8).
10...♕b6 11 ♘e5
Now 11...♖d8 12 ♕c2 ♗h5 or 11...♗f5 is equal.
11...♗h5? 12 b4!
White sees an opportunity for a nice positional advantage, 12...♘a6 13 a3! and 14 c5. Note the tactics in the background (13...♖d8 14 ♕a4 ♕c7? 15 ♘xc6!). Or 12...♘cd7 13 ♘xd7 ♘xd7 14 ♘e4! and ♘d6+.
12...♕xb4? 13 ♕d6 ♕b6!
Question 407: Why not 13...♕xc3 ?
White can capture on c6 – or try to improve with a zwischenzug, 14 ♖ab1? That would win after 14...♕d8 15 ♕xc5 or 14...♕a5 15 ♖xb7!.
But Black has a favorable counter-zwischenzug, 14...♖d8!. For example, 15 ♖xb6 ♖xd6 16 ♖bb1 ♘fd7!.
14 ♘xc6 bxc6
Black must have expected 15 ♗xc6+ ♘cd7. He would be worse after 16 c5 or 16 ♖ab1 but not immediately lost.
15 ♖ab1!
This is the true in-between move: 15...♖d8 16 ♗xc6+ or 15...♕d8 16 ♕xc5 is hopeless.
15...♕a5 16 ♗xc6+ ♘cd7 17 ♗xa8 ♕xc3 18 ♗c6 ♗xe2? 19 ♖b8 mate.
Valery Loginov White
Robert Hafner Black
Velden 1996
1 ♘f3 d5 2 g3 ♘f6 3 ♗g2 c6 4 0-0 ♗g4 5 c4 e6 6 d3 ♘bd7 7 cxd5 exd5 8 ♕c2 ♗d6 9 e4 0-0 10 ♘c3 ♖e8 11 h3 ♗h5 12 ♘h4 dxe4 13 dxe4 ♘b6 14 ♘f5 ♗g6 15 ♘xd6 ♕xd6 16 ♗f4 ♕b4 17 ♖fe1 ♘c4 18 ♖e2 ♘d5 19 a3 ♕f8? 20 ♘xd5 cxd5 21 ♕b3 ♕e7? 22 ♖ae1 ♖ac8 23 exd5 ♕xe2 24 ♖xe2 ♖xe2 25 ♕xb7 ♖ce8 26 d6 resigns.