1. e2e4  1... e7e5  2. g1f3  2... g8f6  3. f3e5  3... d7d6  4. e5f3  4... f6e4  5. b1c3  5... e4c3  6. d2c3  6... f8e7  7. c1f4  7... e8g8  8. d1d2  8... b8d7  9. e1c1  9... d7c5 This is by far Black's most common plan. The knight is on an active square, and the light-squared bishop can soon be developed. But there's also a problem: one cannot fail to notice that the knight is far from the king now, and the monarch feels a bit insecure in a situation with castling on different flanks. 10. h2h4 [%c_effect h4;square;h4;type;GreatFind;persistent;true] The most unpleasant reaction. The pawn supports a knight jump to g5. 10... f8e8  11. f3g5 [%c_effect g5;square;g5;type;GreatFind;persistent;true] This is the main idea of White's previous move. It's not easy to live with such a knight nearby, so Black attacks it.