Sharp moves can be good in some positions but very bad in others that look very similar.
Mikhail Tseitlin White
Georg Danner Black
Budapest 1989
Modern Defense B06
1 d4 d6 2 e4 g6 3 ♘c3 ♗g7 4 ♘f3 c5?
Attacking the center with ...c5 works well in several similar positions, such as 4 f4 ♘f6 5 ♘f3 c5!, because of 6 dxc5 ♕a5! (7 cxd6 ♘xe4!).
5 dxc5! ♕a5? 6 cxd6!
This is different: Black lacks the crucial ...♘xe4.
6...♗xc3+ 7 bxc3
He would be in trouble on the e-file after 7...♕xc3+ 8 ♗d2 ♕c6 9 dxe7 ♕xe4+ 10 ♗e2. For example, 10...♘xe7 11 0-0 and ♖e1.
7...♘c6 8 ♗d2 exd6 9 c4! ♕a3 10 ♖b1
Black has two lingering problems. One is weakness on dark squares, e.g. 10...♘e5 11 ♗b4 (11...♕a4? 12 ♘xe5 dxe5 13 ♕d6!). The other is his vulnerable queen (11...♕xa2 12 ♗c3! f6? 13 ♖a1! and wins).
10...♘ge7? 11 ♖b3!
The dark square issue is critical after 11...♕a4 12 ♕a1! 0-0 13 ♕f6! and ♗h6.
Question 217: So why not 12...♖g8 ?
Similar is 11…♕c5 12 ♕a1 ♘e5 and now 13 ♗b4 ♕c7 14 c5!.
11...♕xa2 12 ♕c1 ♕a6 13 ♕b2 ♗g4!? 14 c5
Also winning is 14 ♕xh8+ ♔d7 15 ♕xa8.
14...b5 15 ♗xb5 resigns.
Alexander Mashevsky White
Kazmir Venglovsky Black
Kiev 2004
1 e4 c5 2 ♘f3 g6 3 d4 ♗g7 4 ♘c3 d6? 5 dxc5! dxc5 6 ♕xd8+ ♔xd8 7 ♗f4 ♗d7 8 0-0-0 ♘c6? 8...♗xc3) 9 ♘a4! b6 10 ♗b5 ♔e8? 11 ♖xd7! ♔xd7 12 ♖d1+ ♗d4 13 ♘xd4 cxd4 14 ♖xd4+ ♔e6 15 ♗xc6 ♖f8 16 e5 f6 17 ♗d5+ ♔f5 19 g4+ resigns.