Exciting position in a random game of chess

I have been playing a little with the Houdini chess engine and Chess Arena. I limit the ELO of the engine to a set value and then I try to beat it. It's not like playing a human being, but saves me the humiliation of being totally thrashed by another person :) Plus I didn't have Internet. In this case the ELO was set to 1400.

One of the games I played turned out to be extremely interesting (and short). Black tried the Elephant Gambit, to which I replied clumsily, but then it made two horrible mistakes and I saw the correct continuation. What I thought was really interesting is how the computer reacted. In what I thought would lead to some sort of piece advantage after a king and rook fork turned out to be a mating situation. The only solution for the computer was to sacrifice the queen and trying to save her would have resulted in mates or even worse situations.
I will publish the PGN here, so you can explore the variations, but before that I want to point out another greatly interesting move. As the Black queen attempts to escape, the next move is a king-queen-rook fork, yet after the king moves White does not capture the queen but does a seemingly random move: 12. Qd4. Why is that? I leave you to check it out for yourselves!

1. e4 e5 2. Nf3 d5 {The Elephant Gambit} 3. Nxe5 Qf6 4.
d4 dxe4 5. Nc3 Bb4 6.
Bd2 Qf5 {A really bad move giving a 3 point advantage to
White.} 7. Nd5 Bd6 8. c3 {My turn for a bad move,
anything went there, Bc4, g4, but I did this, going back to 1 pawn
advantage.} Bxe5 9. dxe5 Qxe5 {Disastrous move, but interesting. Check out the continuations.} (9.
.. Qd7 {This would have been the only decent move.}) 10. Bf4 Qxf4 {Amazingly, the only move here is to sacrifice the
queen for either bishop or knight. Attempts to save the queen lead to
mate!} (10. .. Qf5 {queen attempts to escape.} 11. Nxc7+ {leads to mate in
1. no matter when the king goes.} Kf8 (11. .. Ke7 12. Qd6#) 12. Qd8#) (10.
.. Qe6 {queen attempts to live just a bit longer.} 11. Nxc7+ {Chessgasm!
and Black's pain is only beginning.} Ke7 12. Qd4 {This is the most
interesting move here and by far the best by Houdini's calculations.} Nf6
(12. .. Nc6 13. Qc5+ Kd8 14. O-O-O+ Nd4 15. Rxd4+ Bd7 16. Qf8+ Qe8 17.
Qxe8#) (12. .. Qc6 13. Bb5 Qf6 14. Qb4+ Kd8 15. Qf8#) (12. .. Qf6 13. Qc5+
Kd7 14. O-O-O+ Qd4 15. Rxd4#) 13. Qc5+ Kd8 14. Nxe6+ Bxe6 15. Qc7+ Ke8 16.
Qxb7 Bd5 17. Qc8+ Ke7 18. Qxh8) 11. Nxf4 Nc6 {White wins
easily from +11 points} 1-0