fredthebear: Black should capture the 6.Nc3?! (the eventual mating piece), by pawn or knight. Also, 7...NxBc4 is winning for Black. - - - - -
White's equal castling line 5.O-O goes:
Two Knights Defense, Yurdansky Attack:
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4 5. O-O Nxe4 6. Re1 d5 7. Bxd5 Qxd5 8. Nc3 Qa5 9. Nxe4 Be6 10. Bg5 h6 11. Bh4 g5 12. Nf6+ Ke7 13. b4
Two Knights Defense, Canal Variation:
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4 5. O-O Nxe4 6. Re1 d5 7. Nc3
If Black instead meets 5.0-0 Bc5, then 6.e5 and it's the Max Lange Attack. See the various possibilities here: https://www.chessvideos.tv/chess-op...
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Or, White can also equalize with the advance 5.e5 instead of castling on the 5th move. Thus, 5.e5 d5 6.Bb5 Ne4 7.Nxd4 Bc5 8.Be3 etc. These notes might be useful: http://www.chesspub.com/cgi-bin/che...
White might try 8.NxNc6 instead of 8.Be3:
Two Knights Defense, Keidanz variation (C55)
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4 5. e5 d5 6. Bb5 Ne4 7. Nxd4 Bc5 8. Nxc6 Bxf2+ 9. Kf1 Qh4
Also, White might try 5.Ng5, the Perreux variation (C55) against the Two Knights Defense. Let's have Michael Goeller explain it:
http://www.kenilworthchessclub.org/...
Here are a bunch of named lines in the Two Knights Defense: http://www.chessarch.com/library/00...