Puzzle of the week #173

Chess Diagram: 

[Event "Puzzle #173"][Date "2011.11.15"][Result "1-0"][SetUp "1"][FEN "2kr3r/pp1b1pb1/1q2p1pn/3pP2p/1P1n1B1P/P1NB1NQ1/5PP1/R3R1K1 w - - 0 1"]

At any moment of our games we have to be alert for signs indicating opportunities to gain advantage. Of course gaining advantage could mean a lot of things from the simplest one: obtaining a better position (ex. faster development), to the ultimate one (checkmate). This week we have an interesting position with a lot of pieces on the board; both sides have managed to come out of the opening in good shape. Black has analyzed the position and decided it could capture the very important d4-pawn, a bold decision nevertheless. Now it is your turn:
a) Looking carefully at the position name the most possible opening they have played
b) Analyse the position and explain why Black's last move 1... Nxd4 is a bold move
c) Propose the best response (plan and line) for White

Total available points for this puzzle is 25. The answers will be published next week together with puzzle #174.

Puzzle #172 solution:
Game Nun, Jiri – Plasgura, Petr, 2001 Schneider Bohemia Open. The majority of your answers were good. You can tell we are slowly moving in the right direction. Since we have discussed your anwers in class, I won't spend too many bits for the solution. The important points were:
a) White has neglected the defence of his castle
b) The g3-pawn and castle pawn structure is pretty solid as it is
c) Black has no less than 5 pieces and the e4-pawn pointing at White's castle. He cannot improve his position further, so it is time to attack!

[Event "Puzzle #172"][Date "2011.10.16"][Result "0-1"][SetUp "1"][FEN "1b2rrk1/3b1ppp/5n1q/1N1P4/p1B1p3/P5P1/1P1NQP1P/R4RK1 b - - 0 1"]1...Ng4 2.h4 e3 3.fxe3 (3.f3 exd2 4.Qd3 Ne5 {Black is up a piece and the attack continues}) (3.f4 exd2 4.Qxd2 Bxb5 5.Bxb5 Qb6+ 6.Kg2 Qxb5 {Black is up 2 pieces}) 3...Rxe3 4.Qd1 Rxg3+ 5.Kh1 Qxh4#

Correct solutions:
Philip, Ziyao, James, Harmony - 18 points
Leo - 16 points
Derrick - 14 points
Alex - 10 points
Leroy - 6 points

Alex = 14 points for puzzle #171
Daniel - 12 points for puzzle #171

Ziyao, Philip - 36 points
James, Harmony - 34 points
Leo - 26 points
Alex - 24 points
Derrick - 22 points
Frank - 14 points
Daniel - 12 points
Leroy - 8 points