[Opening "Bishop's opening: Berlin defense"]
1. e4 e5 2. Bc4 Nf6
Bishops Opening Berlin Defence Black develops a piece he counterattacks against White's King Pawn common continuations next are 3.d3 and 3.d4 the opening can easily transpose into a Vienna Game Kings Gambit or Giuoco Piano IMO.
3. Qe2 c6
My unusaul choice 3.Qe2 move forces David to put on his thinking cap about what he wants to do next.
4. Nf3 Qc7 5. Nc3 Bc5 6. d4 exd4 7. e5 O-O
Dangerous things could have developed after my opponents seventh move if he made a bad decision when let's consider some of the reasons why David castled Kingside and he didn't move the Knight out of jeopardy or to safety on a square like Ng4......
If David played 7. Ng4 then I'd have played 8.Bxf7+ Kxf7 9.Ng5+ if Kg6 10.Qe4+ and if he replied Kh6 I could immediatly win David's Black Queen with 11.Ne6+ g5 12.Nxc7 andI'd be threatning his a8 rook with capture and his Knight on g4 isin jepoardy
If David played 7.Kf8 then 8.exf6 dxc3 9.fxg6+ Kg7 (his King is looking badly exposed here) 10.O-O he has to prooceed with caution.
If David played 7.Nh5 that's no good because of 8.Bxf7+ Kxf7 9.Ng5+ and if 9 Kf8 Qxh5+
winning the knight and threatening checkmate if he plays g6 in this position? then
10. Qf3+ with nowhere to run, let's say David instead of 9.... Kf8 played 9.Kg6 then
10.Qd3+ Kh6 (forced) I'd have played 11.Nf7+ checkmate.
If David played 7.Ng8 8.Bxf7+ Kxf7 9.Qc4+ I saw he couldn't play Kg6 because of 10.Nh4+ Kh5 (forced) 11.Qf7+ and if g6 12.Qf3+ Kxh4 13.g3+ checkmate if David played say 11.Kxh4 that's quite fatal because of 12.Qf4+ Kh5 13.Qg5+ checkmate.
Our Game continued.
8. Ne4 Nxe4 9. Qxe4 d5 10. exd6 Qxd6 11. Bf4 Bb4+
This Bishop move was a fatal mistake he should not have ignored the threat to his Queen.
12. c3 dxc3 13. Bxf7+ Rxf7 14. Bxd6 cxb2+ 15. Ke2 bxa1=Q 16. Qe8+ checkmate.
The moral of this is look at the whole position and consider it carefully if you move too quickly then you'll pay the price like he did and it doesn't matter if you think you have a won game it's not won until your opponent tips his/her King!