Sorry for the late reaction. Clearly, B is the critical line here. I'm not convinced of your piece sacrifice. It would be nice if we could make that work, but maybe we have to look at the main lines with 6...Nxd4.
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 Bc5 5. d4 d5 6. Bxd5
Bb4+ 7. c3 Nxd5 8. exd5 Qxd5 9. cxb4 Qxg2 10. Qf3 Qxf3 11. Nxf3 e4 12. Ng5 Nxb4
13. Na3 Nd3+ 14. Ke2 Bf5 15. Nb5 h6 16. Nxc7+ Kd7 17. Nxf7 Kxc7 18. Nxh8 Rxh8 is just one line where I doubt black's compensation.
I still think 15...0-0 would be fine for Black with that monstrous Knight and two pawns for a piece (16.Nxc7 Rac8 and Black gets open files for both Rooks too) but I'm afraid I don't have many lines or much time to find them for the other idea. Here's a vague sketch:
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.d4 d5 6.Bxd5 Nxd4
A. 7.Nxf7 Qe7
A1. 8.Nxh8 Bg4 9.Qd3 is very complicated. Fritz gives 9...Nxd5 10.c3 with slight advantage to White.
A2. 8.c3 0-0 with various lines that appear to all lead to near equality, for example 9.cxd4 exd4 10.Bg5 c6 11.Bc4 Qxe4+
B. 7.Bxf7+ Ke7 8.Bc4 b5 9.Bd3 h6 with a position very similar to the Bxf7+ lines
Here is a thorough analysis of 6...Nxd4.
A: 7.Bxf7+ Ke7 8.Bc4 b5 9.Bd3 h6 (9...Rf8 is an interesting try. 10.Be3 h6 11.Nf3 Bg4 12.Nbd2 Qd6 with compensation i.e. 13.h3 Nxf3+ 14.gxf3 Be6 15.Qe2 a6) 10.Nf3 (10.c3? hxg5 11.cxd4 Qxd4 when white is having serious development problems. Black has a significant advantage here) 10...Bg4 11.Nbd2 Qd6 12.0-0 Rhf8 13.Nxd4 Bxd4 14.Be2 Bd7 15.Nf3 Bc5 16.Qxd6+ cxd6! and black has great compensation.
B: 7.Nxf7?! Qe7 8.Nxh8 Bg4 and white has four alternatives:
B1: 9.Qd2 Nxd5 10.exd5 (10.c3 Nf6 11.cxd4 Bb4 12.Nc3 Nxe4 13.Qc2 Nxc3 and white is under heavy attack) 10...Bf5 11.0-0 Nxc2 12.g4 Qh4 13.Qg5 Qxg4+ 14.Qxg4 Bxg4 15.Be3 Bxe3 16.fxe3 Nxa1 17.Na3 Ke7 18.Rf7+ Kd6 19.Rxg7 Be2 20.Nf7+ Kxd5 21.Rxh7 and black is better.
B2: 9.Bf7+? Kf8 10.f3 Nxe4 11.fxg4 Qh4+ 12.g3 Nxg3 13.Bg5 Qxg5 14.hxg3 Qe3+ 15.Kf1 Nf5 and black wins.
B3: 9.f3? Nxd5 10.fxg4 Nb4 11.Na3 Qh4+ 12.g3 Qh3 13.c3 Qg2 14.cxd4 Qxh1+ 15.Kd2 Qxe4 and white will not survive.
B4: 9.Qd3 Nxd5 10.c3 Nb4 11.cxb4 Bxb4+ 12.Nc3 (12.Bd2 0-0-0 and black has a crushing attack) 12...Qd7 13.Kf1 Bxc3 14.f3 (14.bxc3 Be2+) 14...Ba5 15.fxg4 0-0-0 and black has great pressure.
A comment by g2-g4 on chesspub regarding the above post.
A brief comment on Conquistador's post about 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.d4 d5 6.Bxd5 Nxd4 7.Nxf7?! Qe7 8.Nxh8 Bg4
Now critical is 9.Qd2 Nxd5 10.exd5 (10.c3
- instead of 10...Nf6 - 11.ed Rxd5 12.dc? ed+ -+, or 12.b4 Bxb4 13.cb Qxb4! 14.0-0 Ne2+ -+, or 12.h3 Qh4 13.cd Rxd4 -+) 10...Bf5 11.0-0 (11.d6!?) Nxc2 12.g4?! (12.Qe2) Qh4 and instead of 13.Qg5 White can force a draw with 13.fg Qg4+ 14.Kh1 Qf3+ =. The only winning attempt here is 12...Nd4 13.Kg2 Bxg4 14.f3 Bxf3 15.Rxf3 Nxf3 16.Kxf3 0-0-0, but it is unclear.
9.Bf7+ Kf8 10.f3? Nxe4 11.fxg4 Qh4+ 12.g3 Nxg3 13.Bg5 Qxg5 14.hxg3 Qe3+ 15.Kf1 Nf5 is won for Black as mate is inevitable. This was played in
. However, there's one more move to be considered. 11.h4 "is a real try for saving the game" (Heisman). But it also fails. 11...Nf5! and now
Sadly for Black, it's not the whole story.
and he can fix a draw with 10...Be2 11.Qh3 Bg4 12.Qd3 or continue 10...Rd8, but after 11.Nc3 White is coming back to life.
After 9.f3? Nxd5 10.fxg4 inclusion of 10...Nb4? is unnecessary: 11.0-0! and the game is not that clear. Better is immediate
with the rest as given by Conquistador (see
). Also, 10.fg is not the only White's option.
9.Qd3 Nxd5 10.c3 Nb4 11.cxb4 Bxb4+ 12.Nc3 Qd7 13.Kf1 Bxc3 14.f3 and Black has spectacular possibility
, exposing enemy's king.
Upd. Conquistador did not mention 8.c3 ("a real try", according to Heisman). Black should play 8...Bg4 trying to change game's flow back into 8.Nxh8 course, e.g.
9.Qd2 Nxd5 10.Nxh8 0-0-0 transposes to 8.Nxh8 Bg4 9.Qd2
9.Qd3 Nxd5 10.Nxh8 Nb4 transposes to 8.Nxh8 Bg4 9.Qd3
Only after 9.f3 there's no variant to transpose to. 9...Nxf3 10.gf Nxd5
An updated analysis of 5.d4
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.d4 d5 and now:
A. 6.dxc5 dxc4 7.Qxd8+ Nxd8 gives easy equality
B: 6.Bxd5 Nxd4
B1: 7.Bxf7+ Ke7 8.Bc4 b5 9.Bd3 h6 (9...Rf8 is an interesting try. 10.Be3 h6 11.Nf3 Bg4 12.Nbd2 Qd6 with compensation i.e. 13.h3 Nxf3+ 14.gxf3 Be6 15.Qe2 a6) 10.Nf3 (10.c3? hxg5 11.cxd4 Qxd4 when white is having serious development problems. Black has a significant advantage here) 10...Bg4 11.Nbd2 Qd6 12.0-0 Rhf8 13.Nxd4 Bxd4 14.Be2 Bd7 15.Nf3 Bc5 16.Qxd6+ cxd6! and black has great compensation.
B2: 7.Nxf7?! Qe7 8.Nxh8 (8.c3 Bg4 9.f3 [9.Qd2 Nxd5 10.Nxh8 0-0-0 transposes to 8.Nxd5 Bg4 9.Qd2; 9.Qd3 Nxd5 10.Nxh8 Nb4 transposes to 8.Nxh8 Bg4 9.Qd3] 9...Nxf3 10.gxf3 Nxd5 11.Qxd5 [11.fxg4 Qxf7 12.Rf1 Nf4; 11.Qe2 Nf4 12.Bxf4 Bxf3 13.Qxf3 Qxf7 14.Nd2 Qxf4] 11...Qh4+ 12.Kd2 Qf2+ 13.Kd3 Bxf3 14.Kc4 Be7) 8...Bg4 and white has four alternatives:
B1A: 9.Qd2 Nxd5 10.exd5 (10.c3 0-0-0!? is untested) 10...Bf5 11.0-0 Nxc2 12.g4 (12.Qe2 may be better) 12...Qh4 (12...Nd4! 13.Kg2 Bxg4 14.f3 Bxf3 15.Rxf3 Nxf3 16.Kxf3 0-0-0) 13.Qg5 Qxg4+ 14.Qxg4 Bxg4 15.Be3 Bxe3 16.fxe3 Nxa1 17.Na3 Ke7 18.Rf7+ Kd6 19.Rxg7 Be2 20.Nf7+ Kxd5 21.Rxh7 and black is better.
B1B: 9.Bf7+? Kf8 10.f3? (10.Qd3! and black can go for the draw with 10...Be2 11.Qh3 Bg4 12.Qd3 or continue 10...Rd8, but after 11.Nc3 White is coming back to life) 10...Nxe4 11.fxg4 (11.h4 Nf5!) 11...Qh4+ 12.g3 Nxg3 13.Bg5 Qxg5 14.hxg3 Qe3+ 15.Kf1 Nf5 and black wins.
B1C: 9.f3? Nxd5 10.fxg4 Nb4? (10...Qh4+!) 11.Na3? (11.0-0) 11...Qh4+ 12.g3 Qh3 13.c3 Qg2 14.cxd4 Qxh1+ 15.Kd2 Qxe4 and white will not survive.
B1D: 9.Qd3 Nxd5 10.c3 Nb4 11.cxb4 Bxb4+ 12.Nc3 (12.Bd2 0-0-0 and black has a crushing attack) 12...Qd7 13.Kf1 Bxc3 14.f3 (14.bxc3 Be2+) 14...Bxf3! 15.gxf3 (15.Kf2 Ba5 which 16.gxf3 Qh3 transposes) 15...Qh3+ 16.Kf2 Ba5 followed by 17...Bb6
C. 6.dxe5 Nxe5 7.Bb3 Qe7 8.Bxd5 Bg4 9.f3 0-0-0 -+ because although Black will lose a pawn or two if White grabs material, his attack is more than powerful enough to make up for it.
D. 6.exd5 Nxd4 =/+ with material even, Black's development gives him an advantage
This forum is for the discussion of the line 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.d4. This is not a very aggressive try for White and Black should equalize with little trouble.
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.d4 d5
A. 6.dxc5 dxc4 7.Qxd8+ Nxd8 gives easy equality
B. 6.Bxd5 is an interesting position. Theory recommends 6...Nxd4 with more complications after 7.Bxf7 or 7.Nxf7, but Fritz gives 6...Bb4+ 7.c3 Nxd5 with equality, for example 8.exd5 Qxd5 9.cxb4 Qxg2 10.Qf3 Qxf3 11.Nxf3 e4 12.Ng5 Nxb4 with an imbalanced, interesting position. Apparently, to prevent Black's Knight from occupying the outpost on d3 White must sacrifice a pawn, giving Black three pawns for a piece.
C. 6.dxe5 Nxe5 7.Bb3 Qe7 8.Bxd5 Bg4 9.f3 0-0-0 -+ because although Black will lose a pawn or two if White grabs material, his attack is more than powerful enough to make up for it.
D. 6.exd5 Nxd4 =/+ with material even, Black's development gives him an advantage