In the scotch, Nxd4 usually isn't the best move. Your opponent castled queenside in this case, but I've gotten some very powerful attacks both on RHP and OTB by playing f4 and castling kingside, i.e.
Here's an example from RHP, admittedly with some big mistakes from my opponent.
Game 7023478
05 Dec 11
Originally posted by DerJagerLook into 4. Bc4!
[pgn]1. e4 e5 2. Nf3 Nc6 3. d4 exd4 4. Nxd4 Nxd4 5. Qxd4 d6 6. Bc4 Be6 7. Be3 Nf6 8. Nd2 c5 9. Qc3 Bxc4 10. Qxc4 Be7 11. 0-0-0 0-0 12. f3 Rb8 13. Nb3 b5 14. Qe2 c4 15. Nc5 Qa5 16. e5 dxc5 17. exf6 Bxf6 18. Bxc5 Qxa2 19. Bxf8 Bg5 [/pgn]
I play as black. 🙂
Any thoughts or analysis is appreciated as I just tend to move with what seems natural rather th ...[text shortened]... n with skill-for example. I almost resigned when my opponent took Bxf8 but I luckily saw Bg5! 🙂