analysis of 5.Nxf7,6,Kf1, 9.d6 Qxd6 10.Nf7

I've only looked at 10.Qe7!?, Jerz' suggestion. Variations C, E and F lose for white, B and D are perpetuals. White may try for an advantage in A (A2, for instance, is not clear, but not very promising either) and H, which may be white's best try.

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 Bc5 5. Nxf7 Bxf2+ 6.
Kf1 Qe7 7. Nxh8 d5 8. exd5 Nd4 9. d6 Qxd6 10. Nf7 Qe7 (A)11. d3
    (B)11. c3 Bg4 12.Qa4+ Nd7 13. cxd4
        (13. Kxf2 Qh4+ 14. Ke3
            (14. Kf1 Bh5 15. Nxe5 O-O-O 16. Nxd7 (16. cxd4? Rf8+
            17. Nf3 Bxf3 18. Qa3 (18. gxf3 Qh3+ 19. Ke1 Qxf3 20. Rf1
            Re8+) 18... Bxg2+ 19. Kxg2 Qf2+ 20. Kh3 Rf3+ With a winning
            initiative.)(16. g3 Qf6+ 17. Kg2 Bf3+ 18. Nxf3 Qxf3+
            19. Kh3 19... Qh5+)
            16... Qf4+ 17. Kg1 Be2 18. h4 Nf3+ 19. Kf2 Nd4+ 20. Kg1)
         14... Kf8 15. Qa3+ c5 16. Nd6 Qg5+ 17. Kf2 (17. Ke4 Nf6+ 18. Kd3 Be2#)
        17... Qf4+ 18. Kg1 Be2 19. h3 Nf3+ 20. Kf2 Nd4+)
    13... Qf6 (13... Bxd4 !?) 14. Nd6+ (14.dxe5? Qf4) 14... cxd6 15. dxe5 Qxe5
    (15... Qf4? 16. Bf7+ Qxf7 17. Qxg4) 16.Bf7+ (16. Kxf2 Qf4+) 16... Ke7 17. Kxf2
    Rf8 18. Qxg4 Rxf7+ 19. Qf3 Qd4+ 20. Ke2 Rxf3 21. gxf3 Ne5 22. Rf1 Qc4+ 23. d3
    (23. Kf2 Nd3+) 23... Qxd3+ with perpetual.)

    (C)11. Nxe5? Qxe5 12. c3
        (12. d3 Bh4 13. Qd2 Nxc2)
        (12. Kxf2 Ne4+ 13. Kg1 Qc5)
    12... Bg4 13.cxd4 (13. Qa4+ Kd8) 13... Qf5 14. Be2 Bh4+ 15. Bf3 O-O-O 16. h3
    Qd3+ 17. Kg1 (17. Qe2 Re8) 17... Qxd4+ 18. Kh2 Qd6+ 19. Kg1 Re8 20. Bxg4+ Kb8
    21. Nc3 Qd4+ 22. Kh2 Qf4+)

    (D)11. Ng5 Bg4 12. Nf3 e4 13. h3
        (13. Kxf2? O-O-O 14. Re1
            (14. h3 exf3 15. hxg4 Nxg4+ 16. Kg3 Ne3 17. dxe3
                (17. Qxf3 Nef5+ 18. Kf2 Nxf3 19. gxf3 Qc5+ 20. Kg2 Qxc4)
            17... Qg5+)
        14... Qd6 15. Re3 Bxf3 16. gxf3 Qxh2+)
        (13. Be2? exf3 14. gxf3 Bh4 15. fxg4 O-O-O With a typically strong attack.)
    13... exf3 14. hxg4 fxg2+ 15. Kxg2 Qe4+ 16. Kxf2 Nxg4+ 17. Kg1 Nf3+ 18. Kf1 Nfh2+
    19. Kg1
        (19. Rxh2? Qf4+ 20. Ke1 Qg3+ 21. Ke2 Qxh2+ 22. Kf3 Kd7 23. Kxg4 Rf8 With
        a mating attack.)
    19... Nf3+)

    (E)11. Kxf2? Ng4+ 12. Ke1 Qf6 13. Rf1 Qh4+ 14. g3 Qxh2 15. d3 Qxg3+ 16. Kd2 Qe3+
    17. Kc3 Ne2+ 18. Qxe2 (18. Kb3 Qb6+ 19.Ka3 Qa5+ 20. Kb3 Nd4#) 18... Qxe2 19. Rh1
    Qf2 With a winning initiative.)

    (F)11. b3? Bg4 12. Ba3 Qd7 13. Nxe5 (13. Qc1 Qf5) 13... Qf5 14. Nf3 Nxf3 15. gxf3
    Bxf3 16. Qc1 Qh3+ 17. Kxf2 Ng4+)

    (G)11. h3!? Bh4 12. c3 (12. Nc3 Nh5) 12... Nf5 13. Qb3
        (13. Na3 Ne4 14. d3 Qf6 15. Qf3 Nfg3+ 16. Kg1 Ne2+ 17. Qxe2 Bf2+
        18. Kh2    Bg3+)
        (13. d4 exd4 14. cxd4 Be6 15. Bxe6 Qxe6 16. Ne5 O-O-O 17. Nf3 Ng3+
        18. Kg1 Ne2+ 19. Kf1 Ng3+)
    13... Qc5 14. Qb5+ Qxb5 15. Bxb5+ Kxf7 Black has an initiative,
    but this may be good for white.)

(A ctd.)11... Bg4 12. Qd2 Bh4 13. Nc3
    (13. Qe3 Be2+ 14. Qxe2 (14. Kg1 Ng4) 14... Nxe2 15. Kxe2 b5 16. Bb3 c5
    The knight on f7 is in trouble.)

13... b5!! 14. Nxe5!
    (14. Bxb5+ Nxb5 15.Nxb5
        (15. Ng5 Nd4 16. h3 Qf8 17. Kg1 Qc5 18. Kf1 (18. Qe3 Bxg5)
        18... Qf8 A very interesting perpetual.)
    15... Qxf7)

    (14. Nxb5? Ne4!! 15. dxe4 Qf6+ 16. Kg1 Ne2+ 17. Qxe2 Bxe2 18. Nxc7+
        (18. Be3 Bxc4 19. Nxc7+ Kxf7 20. Nxa8 Qc6)
    18... Kd7 19. Be3 Bxc4 20. Nxa8 Qxf7 21. g3 Qg6 22. Rd1+ Kc6)

(A ctd.)14... O-O-O! (A1)15. Nf3
    (A2)15. Nxg4!? Rf8 16. Ne5
        (16. Nf2 Bxf2 17. Be6+
            (17. Kxf2 Ne4+ 18. Kg1 Nxd2 19. Bxd2 Qc5)
            (17. Qxf2 Ng4 18. Be6+ Nxe6 19. Qf3 Nd4)
        17... Nd7 18. Bxd7+ Kxd7 19. Qxf2 Rxf2+ 20. Kxf2 Qf6+ 21. Kg3
        (21. Ke1 Nxc2+) 21... Qg6+ 22. Kf2 perpetual. (22. Kh3? h5
        23. g3 Qf5+ 24.Kg2 Qf3+ 25. Kg1 h4 26. gxh4 b4))
    16... Ne4+ 17. Qf4 Rxf4+ 18. Bxf4 Nd2+ 19.Bxd2 Qxe5 20. g3 bxc4 21. Kg2 Bf6 unclear)
   
    (A3)15. Nxb5? Qxe5 16. Nxd4 Rxd4 17. Kg1 (17.c3 Ne4 18. Qc2 Nxc3 19. bxc3 Qe1#)
    17... Ne4 18. Qe3 (18. Qf4 Bf2+ 19. Kf1 Ng3+) 18... Bf2+ 19. Qxf2 Nxf2
    20. Kxf2 Rf4+ 21. Bxf4 Qxf4+ 22. Kg1 Qe3+)

    (A4)15. Bxb5? Qxe5 16. Qe3 (16. h3 Qg3 17. hxg4 Rf8) 16... Qf5+ 17. Qf4 Qe6 18. Qe3
        (18. Bd2 Nh5 19. Bc4 Be2+ 20. Kg1 Qb6 threatening Nf3+. 21. Be6+ an
        interesting resource, blocking the 6th rank.
            (21. Qe3 Nf3+ (21... Bg5 22. Qf2 Bxd2 23. Nxe2 Nxe2+))
        21... Kb8 (21... Nxe6+ 22. Qe3) 22. Qe3 Bg5! 23. Qf2 Bxd2 24. Nxe2 Nxe2+
        25. Kf1 Qxe6)
    18... Qf7 19. Kg1 (19. Qf4 g5) 19... Nxb5 20. Nxb5 Re8)

    (A5)15. Qe3!? Nxc2 16. Qxa7 Qxe5 17. Qa6+ Kd7 18. Qxb5+ (18. Bxb5+ ?? Ke7)
    18... Qxb5 19. Bxb5+ c6 20. Ba4 Rf8 21. Bxc2 Nd5+ 22. Kg1 Bf2+ 23. Kf1 Bh4+)

(A1 ctd.)15... Nxf3 16. Qe3
    (16. gxf3? Bh3+ 17. Kg1 bxc4 18. Qe3 Ng4 19. fxg4 Rf8 20.Bd2 Qf6 21. Qf4
    (21. Qe2 Bf2+) 21... Qb6+ 22. d4 Rxf4)
16... Re8 17. Qxe7
    (17.gxf3 Qf8 18. Ne4 Nxe4 19. dxe4 Bxf3 20. Qf4 Qxf4 21. Bxf4 Bxh1 22. Bxb5 Rxe4)
17... Rxe7 18. Bf4 bxc4 19. h3
    (19. gxf3 Bxf3 20. Rg1 Ng4 21. dxc4 Rf7 22. Bg3 Bg5 23. Ke1 Re7+ 24. Kf1 Rf7)
19... Bh5 20. gxf3 cxd3 21. cxd3 g5 22. Bd2 Bxf3 23. Rh2
    (23. Rg1 g4 24. hxg4 Nxg4 25. Bf4 h5)
23... Bg3 24. Bxg5 (24. Rf2 Bxf2 25. Kxf2 g4) 24... Bxh2 25. Bxf6 Re3 26. d4 Bb7
27. Re1 Rf3+ 28. Kg2 Re3+ 29.Kf2 Rf3+ 30. Kg2

I went through all the variations and it looks like black has equalized in all lines with best play.  10...Qe7 is much better than the previous 10...Qc5.  White's only hope lies in the endgame with two rooks versus the queen.  Note how the following line is similar to the one I gave after 10...Qc5 except the queen is better placed.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kf1 Qe7 7.Nxh8 d5 8.exd5 Nd4 9.d6 Qxd6 10.Nf7 Qe7 11.d3 Bg4 12.Qd2 Bh4 13.Nc3 b5 14.Nxe5 0-0-0 15.Nxg4 Rf8 16.Ne5 Ne4+ 17.Qf4 Rxf4 18.Bxf4 Nd2+ 19.Bxd2 Qxe5 20.g3 bxc4 21.Kg2 Bf6 22.dxc4

White may be able to squeeze something out of the endgame, but it will be difficult against black's activity.  Thiss is better than 15.Nf3 because that leads to a favorable endgame for black.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kf1 Qe7 7.Nxh8 d5 8.exd5 Nd4 9.d6 Qxd6 10.Nf7 Qe7 11.d3 Bg4 12.Qd2 Bh4 13.Nc3 b5 14.Nxe5 0-0-0 15.Nf3 Nxf3 16.Qe3 Re8 17.Qxe7 Rxe7 18.Bf4 bxc4 19.h3 Bh5 20.gxf3 cxd3 21.cxd3 g5 22.Bd2 Bxf3 23.Rh2 Bg3 24.Bxg5 Bxh2 25.Bxf6 Re3 26.d4 Bb7 27.Re1 Rf3+ 28.Kg2 Rg3+ 29.Kf1 Rxh3 30.Re8+ Kd7 31.Rb8 Bh1 32.Rh8 Ke6 33.Be5 Bxe5 34.Re8+ Kd7 35.Rxe5 Bb7 36.Na4 Bc6 37.Ra5 Rh4

White is fighting for a draw, black has a modest advantage in the endgame.

The problem is that the resulting position will leave two rook pawns, opposing b and c pawns, Rooks, and the minor pieces on the board.  Even though white is fighting for a draw, it should still end as a draw based on the structure of the position.  Black's minor piece advantage is his only hope for a win.  

What is the refutation of 10...Qc5?

Okay so this was what I saw from the original thread.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kf1 Qe7 7.Nxh8 d5 8.exd5 Nd4 9.d6 Qxd6 10.Nf7 Qc5 and now:

11.d3 Bg4 12.Qd2 was the critical line where white had a pretty solid advantage.

Example line:

12...Bh4 13.Nc3 b5 14.b4 Qb6 15.Nxe5 bxc4 16.Nxc4 Qe6 17.h3 Nh5 18.Kg1 Nf4 19.Kh2 Bxh1 20.Qe3 Bc6 21.Qxd4

10...Qe7 is clearly the better move for black.

There are some interesting analyse on chesspublishing

IMO 9.-cd6 is 'under a cloud'

So it will be nice if someone have time to complete the group's work inthe 9.-Qd6

line!

I think that 9...Qxd6 has already been for the most part completed and shown to be = for black.  It appears as if 9...cxd6 gives white the advantage with best play.  So clearly 9...Qxd6 must be played.

A post on chesspub by g2-g4.

@Master Om, just to save your time.

micawber wrote on 09/01/10 at 18:25:01:

I looked at this variant several years ago, and found it being lost for White.
15...Qxg3+ 16.Kd2 Qe3+ 17.Kc3 Ne2+ 18.Qxe2 (after 18.Kb3 or 18.Kb4 White is mated) 18...Qxe2 and now b7-b5 is a really annoying threat to f7 knight. White will have to give up at least one piece with his king still being overexposed.
A. 19.Rh1 b5 20.Bd5 a5! -+
B. 19.Nd2 Ne3 -+
C. 19.d4 Qe4 20.Kb3 b5 21.Bxb5 Bd7 22.Nc3 Qb7 -+

Also, in another sub-variant of 4C
micawber wrote on 09/01/10 at 18:25:01:

Black has a stunning 13...Ng4! -+

As to de Zeeuw's "refutation №1", Black has
8...Bh4 and now
A. 9.Bxd5 Bg4 10.Qd2 (or 10.Bxc6 bc 11.Qd2 Nxe4! 12.de Qf6+ with soon mate) Nxd5 followed by 11...Nd4 is a disaster for White, e.g. 11.ed Qf6+ 12.Kg1 Nd4 or 11.h3 Nd4 12.hg Qf6+ 13.Kg1 Nd4 14.Nc3 Nfe2+
B. 9.ed Bg4
    B1 10.Qd2 Nd4 11.Qe3 Nxc2 12.Qd2 Nd4! 13.Qe3 Be2+ 14.Qxe2 Nxe2 15.Kxe2 Qd7 -+
    B2 10.dc Bxd1 11.cb Rb8 12.Nc3 (Ne4 was threatening) Bxc2 is decisive.
C. 9.Bb5 Bg4 10.Qd2 0-0-0 11.h3 allows 11...Nxe4!? to be played right now 12.de Qf6+ 13.Ke2 Nd4+, but 11...Qc5 could be even stronger, since micawber's 13...Nxe4! definitely works. Perhaps, White has to remove bad knight c6. 10.Bxc6!? bc 11.Qd2, but it should not help either. 11...Nxe4! 12.de Qf6+ 13.Kg1 0-0-0 and now after 14.h3 de 15.Qxd8 Qxd8 16.Kh2 (otherwise 16...Qd1+ or 16...Qd4+ are murderous) Bf2 (threat Qh4) Black should win.

Refutation №2

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kf1 Qe7 7.Nxh8 d5 8.exd5 Nd4 9.h3 Bh4 10.d6 Qxd6 11.Nf7 Qc5 12.Na3 e4
After 12...Ne4!? White escapes with 13.Nd6+! the beginning of long combination 13...cxd6 14.Qh5+ g6 15.Qxh4 Nf5 16.Bb5+ Bd7 17.Bxd7+ Kxd7 18.Qxh7+ Kc6 19.d4 Qxd4 20.Qc7+ Pointe! 20...Kxc7 21.Nb5+ Kd7 22.Nxd4 Nxd4 23.c3 Ng3+ 24.Kg1 Nde2+ 25.Kh2 Nxh1 26.Kxh1 Nxc1 27.Rxc1 Rf8 and in this endgame White is only slightly worse.
13.g4

(apart from 13...Be6, which also may be good) Black develops his knight to g3 or f4. Tactical basis is simple: 14.gxh5?? Qf5+ and mate in two. White has several possibilities:
A. 14.Rg1 Qe7 15.Rg2 (15.Kg2 Nf4+ 16.Kh2 Nf3+ 17.Kh1 Bf2–+) 15...Qf6+ 16.Kg1 Nf4 17.Qf1 (17.Nb5 Nxh3+–+; 17.Kh1 Nxg2 18.c3 Ne1 19.cxd4 Be6 20.Qe2 Bxf7 and despite temporarily equal material White is lost, e.g. 21.Qxe4+ Kd7 22.Qf5+ Qxf5 23.gxf5 Rf8 and Black begins his harvest; 17.c3 Nxh3+ 18.Kh2 Nf3+ 19.Kxh3 Be1 20.Qxe1 Nxe1 21.Be2 Qxf7–+) 17...Be6 18.Kh1 (18.Bxe6?? Nxh3+–+) 18...Bxc4 19.Nxc4 Qxf7 20.Rh2 Bg3;
B. 14.d3 e3 15.Bxe3 Ng3+ 16.Ke1 Nge2+ 17.Kf1 Qc6 18.Bb5 Nxb5 19.Nd6+ (19.Kxe2?? Qg2+ 20.Bf2 Qxf2#; 19.Rh2 Qf3+ 20.Bf2 Nbd4–+) 19...cxd6 20.Qxe2 Qxh1+ 21.Bg1+ Kf8 22.Nxb5 Qxh3+ 23.Qg2 Bxg4 with pair of bishops and an extra pawn in endgame;
C. 14.Rh2 Be6
   C1. 15.Bxe6 Ng3+ 16.Kg2 e3 17.dxe3 Qc6+ 18.Kg1 Nde2+ 19.Kf2 Qxe6 20.Nd6+ (20.Ke1 Qxf7–+) 20...cxd6 21.Ke1 Qe4–+;
   C2. 15.gxh5 Bxc4+ 16.Nxc4 Qxc4+ 17.Kg1 [17.d3 Qxf7+ 18.Kg2 (18.Kg1 Nf3+–+) 18...exd3 19.cxd3 Qd5+ 20.Kf1 Bg3–+] 17...Nf3+ 18.Kh1 Nxh2 19.Kxh2 Qxf7–+; and finally,
   C3. 15.d3 Ng3+ 16.Kg2 ed -+

Refutation №3 (just developing John Jerz' variant from -0.36 to -1.5 at least  )

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kf1 Qe7 7.Nxh8 d5 8.exd5 Nd4 9.Be2 Bh4 10.c3? Nxe2 11.Qxe2 Bg4 12.Qb5+ Nd7 13.Kg1
But let's first take a closer look at 13.g3, because there are a few inaccuracies in Heisman’s CD 13…Qf6+ 14.Kg1 Bh3 15.Qe2 0–0–0 16.d4 (Not better is 16.d3 Rf8 17.Nd2

–+) 16...Rf8 17.Nd2 (or 17.Bf4 exf4 18.Nd2 f3 19.Nxf3 Bg4 20.Rf1 Bxf3 21.Qe6 Bg5 22.h4 Bd2 23.Kh2 g5–+)

“seems less accurate”, according to Heisman, but in fact is the strongest here 18.Nf3 Qxf3 19.Qxf3 Rxf3 20.Bf4 Bf6–+
13...Qf6 14.Qf1 (14.g3? Bh3 15.Qe2 to cover f3 15...0–0–0 16.d3 Rf8 17.Bf4 exf4 18.Nd2 Ne5–+) 14...Qb6+ 15.d4 0–0–0 at this point J.Jerz's analysis ends. It is clear that Black has an adequate attack for sacrifice, but let's look a bit further.
   A. Simple development does not help: 16.Nd2 Rf8 17.Nf7 (17.Qd3 exd4 18.Nf3 Ne5 19.Qxd4 Qxd4+ 20.cxd4 Nxf3+ 21.gxf3 Bh3–+; 17.Nf3 exd4 18.Qd3 Ne5 transposes to 17.Qd3) 17...exd4 18.Nc4 Qg6 19.Nfd6+ Kb8 20.Bf4 Bg5–+;
   B. 16.g3 (to secure e1 square for his queen) 16...Rf8 (Buecker in his chesscafe article, quoting Pastore?) 17.Nf7 (17.Qe1? exd4–+) 17...Qg6 along with other threats, it is h4-bishop protection. 18.Be3 (18.d6 Rxf7 19.Qc4 c6–+; 18.Nd2 Rxf7 19.Qe1 Bh3–+; 18.Qe1 Bh3 19.Be3 Qxf7 20.Nd2 exd4 21.cxd4 Qxd5 22.Qe2 Bf6–+) 18...exd4 19.Bxd4 Rxf7 20.Qe1 Re7 21.Qf1 Bg5–+;
   C. 16.Qd3 Rf8 17.g3 (for 17.Nd2 exd4 18.Nf3 Ne5–+ see 16.Nd2) and Black can keep attacking 17...exd4 18.Qxd4 Bh3 19.Nd2 Qd6–+, or simply grab pieces back 17...Bg5 18.Bxg5 Qxb2 19.Nd2 Qxa1+ 20.Kg2 Qxa2 21.Rf1 Qxd5+ 22.Kg1 Rxh8 two pawns up, eventually.
   D. 16.Nf7 Rf8 17.g3 Qg6 transposes to 16.g3

Comment on refutation 4C2

After 13.h3 Black doesn't have to make a perpetual with 17...Nf3+, but should rather go on with

(threat 18...Ne3+), e.g. 18.Kf1 0-0-0 19.d3 Re8, or 18.Qe1+ Ne3+ 19.Kf2 Qf6+! 20.Kxe3 0-0-0.
Next, 13.Kxf2 0-0-0 14.Nxd4 Bxd1 15.c3 is given as 0.00, however Black is winning here with either 16.Ke1 Bf3! or 16.Ke1 Bg4