I call this the main line because I have played it most often. The simple idea is to get the Bishop-pair.
6. -Bxc3+ 7. bxc3 c5 8. Be2
Better is 8. Be3.
8. -Nc6 9. fxe4
9. Be3!.
9. -Nxe4
9. -cxd4 10. e5 Ne4! 11. cxd4 Qxd4 12. Qxd4 Nxd4 13. Bd1 -+.
10. Qd3 Nf6 11. Nf3 O-O 12. O-O
If White can do this good in the opening, the sacrifice is well justified. One could say that White has attacking chances for his Pawn; I would say that Black has a Pawn for White's attack.
12. -Kh8
Black is already defending himself, which makes it easy for White to arrange the attack. A natural would be 12. -b6 13. Bd1 Bb7 14. Bc2 Nce7 15. Ng5 Ng6 16. Qh3 h6 (otherwise 17. Rxf6!) 17. Nxe6! with decisive advantage.
13. a4 Ng8 14. Bd1
This Bishop manoeuvre makes the decisive mate threat.
14. -Nce7 15. Bc2 Ng6
Stronger is 15. -f5 16. Ne5 Nc6 17. Ng6+!? hxg6 18. Qh3+ Nh6 19. Bxh6 with good attack, even though Black avoided the trap 19. -gxh6? 20. Qxh6+ Kg8 21. Qxg6+ Kh8 22. Rf3 Qh4 23. Rg3! (23. Rh3? Qxh3 24. gxh3 Rg8) Qh7 24. Qg5 with the idea Rf1 +-.
16. h4
Deadly is also 16. Ne5! Qe7 (16. -f5 17. Nxg6+ hxg6 18. Qh3+ just like after 15. -f5, but without the Knight sacrifice) 17. Qh3 Nh6 (17. -Nf6 18. Bxg6 winning Knight) 18. Bxg6 fxg6 (18. -hxg6 19. Bxh6 gxh6 20. Qxh6+ Kg8 21. Rf3 with decisive attack) 19. Bxh6 gxh6 20. Qxh6 Kg8! 21. Nxg6!! hxg6 22. Qxg6+ Qg7 (22. -Kh8 23. Rxf8+ Qxf8 24. Rf1) 23. Rxf8+ Kxf8 24. Rf1+ Kg8 25. Qe8+ 1-0.
16. -h5
Better is 16. -f5 17. h5 N6e7 18. g4!? with attack.
17. Ng5
Still is good 17. Ne5! Nf6 (17. -Qe7 and 17. -N8e7 would be met by 18. Rxf7 with superior game) 18. Nxg6+ fxg6 19. Qxg6 Kg8 20. Rxf6! Qxf6 (20. -Rxf6 is not better) 21. Qh7+ Kf7 22. Qxh5+ g6 23. Qh7+ 1-0.
17. -Nh6
18. Ba3
18. Rxf7! Rxf7 (18. -Nxf7 19. Qxg6 Nxg5 20. Bxg5) 19. Nxf7+ Nxf7 20. Qxg6 Kg8 21. Bg5! Nxg5 22. hxg5 Kf8 23. Rf1+ Ke7 24. Qxg7+ Kd6 25. Qe5+ Ke7 26. Qxc5+ 1-0.
18. -b6 19. d5 exd5
Now White gets rid of his doubled c-Pawns, and opens the decisive diagonal a1-h8. Black could have tried 19. -Nf5.
20. cxd5 a5
Seems like resignation. 20. -f5 is better.
21. c4 Bd7 22. Bb2
Sadistic pleasure! Instead of playing 22. Nxf7+! Rxf7 23. Rxf7 Nxf7 24. Qxg6 Kg8 25. Bb2 1-0, White just increases the pressure by developing the last pieces to ideal squares.
22. -Qe7
Here was the last chance to play 22. -f5 23. Rae1 Ng4 with unclear game, but not 23. -Nxh4? 24. Qg3 Ng6 25. Ne6! Qe8 (25. -Bxe6 26. Qxg6) 26. Nxg7 Qf7 27. Nxf5+ Kh7 28. Nxh6 1-0.
23. Rae1
Ever seen a harmonic position?
23. -Qd6 24. Qc3
Materialist would have won with 24. Be5 Bf5 25. Rxf5.
24. -Rg8 25. Rxf7 Nxh4
More active is 25. -Ng4 26. Rxg7, and Black would get a few check.
26. Qxg7+!
It is always nice to end with a Queen sacrifice.
26. -Rxg7 27. Bxg7+ Kg8 28. Bh7#