DAY 90 Mated in 20 moves

Moves preceding a blunder may make a lot of sense.
I know from experience.

Yehuda Gruenfeld White

Andrew Soltis Black

Lone Pine 1979

Modern Defense B06

1 e4 g6 2 d4 g7 3 c3 d6 4 f3 a6 5 e2 b5 6 0-0 b7

I wanted to win the e-pawn, after 7...b4 8 d5 e6.

7 g5 d7

White was poised for 7...f6 8 e5! dxe5 9 xe5, with advantage (9...0-0 10 f3).

8 e1 h6 9 h4 b6

I rejected the consistent 9...g5 10 g3 e6 because 11 e5 dxe5 12 xe5 is a bit worse for me.

10 a3 c5

But 10...g5 11 g3 f6 was reasonable (12 d3 h5 and ...xg3).

11 e5 cxd4

Yes, it’s risky to open the position when uncastled. But his center is collapsing.

12 xd4 dxe5 13 e3 c7 14 g3! f6?? 15 h4! f7

Now I expected 16 d3 f5, when 17 xe5 xe5 18 xe5 xe5 19 xe5 d7 looked defensible.

Illustration

But instead there came:

16 d3! f5

Or 16…e4 17 xe4 d7 18 d6+! and 19 xg6+.

17 xg6!

Murderous (17...xg6 18 h5+! mates).

17...d7 18 h5 xd3 19 f4+ resigns.

It’s 19...f8 20 e6 mate or 19...f6 20 h4 mate.

Eduardas Rozentalis White

Alexander Wojtkiewicz Black

Geneva 1990

1 e4 g6 2 d4 g7 3 f3 d6 4 c3 a6 5 e2 b5 6 0-0 b7 7 g5 d7 8 e1 h6 9 h4 c5 10 a4 cxd4 11 xd4 bxa4 12 xa4 c5 13 b4 f6 14 d5 e6 15 xb7! (15...xb7 16 c6) exd5 16 c6 xb7 17 xd8 and wins.

Question 99: Why not 14…xd5 15 exd5 xd5 ?