Naselwaus / MouseTrap gambit

I'm kinda confused, what's the point of Bg5?

Check out Stephen Bucker's evaluation, be prepared for a long read though! :

The Mousetrap Gambit Owen’s Defense is a rare guest in tournament play, so few players find it necessary to prepare for it and I was no exception. However, in 1979 I lost a club game against 1...b6. I swore that in my next encounter with 1...b6 my opponent would face a hard fight from the first moves. My analysis produced a strange looking gambit. Four years later, in a small German round robin tournament, the opportunity came to test the new idea.

Over the Horizons Stefan Bücker

St. Bücker – A. Muellen Wittlich 1983 Owen’s Defense [B00] 1 e4 b6 2 d4 Bb7 3 Bg5 Sacrificing a center pawn. This can’t be correct – or can it? 3...Bxe4 “White has given up an important asset at e4, and is not even ahead in development. This gambit is entirely lacking in motivation or justification. It seems to be one of those situations where someone made up a gambit just for the fun of it, but I doubt White is finding the experience enjoyable!” (Eric Schiller, Unorthodox Chess Openings [2]). Just for the fun of it? Today I know of eleven games played with 3 Bg5. White scored nine out of eleven, 82 percent. Not too bad for a gambit “entirely lacking in motivation or justification.” In his first sentence, the American author shows a typical reaction: he thinks that White’s sacrifice is merely an attempt to get a lead in development. This is exactly where I started – see the comment to the next move – before I found a refinement:

4 d5! 4 Nd2 Bb7 5 Bc4 had been my first idea to justify the sacrifice: 5...Bxg2 6 Ngf3 Bxh1?? Now White has a substantial lead in development, sufficient for a decisive blow: 7 Bxf7+! Kxf7 8 Ne5+ Ke6 (8...Ke8 9 Qh5+ g6 10 Nxg6 and wins. Note that the whole combination doesn’t work, when White has played 4 Nc3 instead of 4 Nd2, because then Black has 10...Bf3!, which turns the tables) 9 Qg4+ Kd6 10 Nf7+ Kc6 11 Nxd8+ Kb5 12 Qe2+ Ka5 13 Nb3+ Kb4 14 Bd2+ Ka4 15 Qc4 mate. Obviously, Black’s sixth move is a serious mistake. After 6...d5 7 Rg1 dxc4 (better than 7...Bh3 8 Bd3 Nc6 9 Ne5) 8 Rxg2 b5 9 a4 c6 10 Ne4 Black’s position is preferable. Not to take on g2 immediately seems even better: 5...f6 6 Bd3 e6 (or 6...g6 7 Be3 Bxg2 8 Qg4 Bd5 -/+) 7 Bf4 Bxg2 8 Qh5+ Ke7 -+. And of course Black has the cautious alternative 5...d5, when White also doesn’t have enough for his pawn. I also didn’t trust the “quiet” continuation 4 Nc3 Bb7. One game went: 5 d5 c6 (5...Nf6) 6 Bc4 cxd5 7 Bxd5 Bxd5 (7...Nc6 followed by Nf6 and e6 seems preferable) 8 Nxd5 Na6 9 Qe2 Nc7 10 0-0-0 Nxd5 11 Rxd5 Qc7 12 Nf3 Nf6 13 Rd3 h6 14 Bxf6 gxf6 15 Rhd1 Rd8 16 Nd4 e6 17 g3 Be7 18 f4 f5 19 Nb5 Qb8 20 Nd6+ Bxd6 21 Rxd6 Ke7 22 Qd2 Qc7 23 Qb4 Ke8 24 g4 fxg4 25 f5 Rg8 26 Qa4 Ke7 27 Qf4 += Qc5? 28 f6+ Ke8 29 Rxd7! +- and White won, Kettner – Villing, Donaueschingen 1985 (Baden Championship). Schiller’s continuation is too slow: 4 c4?! Bb7 5 Nc3 h6 6 Bh4. He states, “White tries to keep Black from advancing the e-pawn. Here, however, Black can afford to adopt an unorthodox double fianchetto.” 6...g5 7 Bg3 Bg7 8 Nf3 c5 9 d5 Bxc3+ 10. bxc3 Nf6, and “Black will finally play ...e6.” So when Eric Schiller condemned my gambit, he didn’t even know the fourth move of my analysis, which I had published in 1983 (second edition 1984 [1]). The text move is the key to the whole Mousetrap concept. The black b7bishop (“the mouse”) has left its mouse-hole to eat the white “cheese” e4. Now the trap closes with a snap (4 d5!). Obviously the mouse is not dead, but it seems the trap has hit her tail, as she cannot return to b7. Back to chess – here it also makes sense to separate the bishop from its “hole.” Without the bishop, the pawn structure a7-b6-c7 is weakened. And there is more – the whole black position is in some disorder. The

Latin phrase “divide et impera” (divide and conquer) characterizes White’s intentions. The game continuation will show what is meant. 4...f6 5 Nc3 White chases the bishop to g6, followed by fast development (Qd4, 0-0-0) with threats on both wings (h4, Nf3-e5 or Nf3-d4, Bb5 or Bd3). To find good squares for Black’s pieces is more difficult – especially for his king and b8-knight. The Zygmunt St. Nasiolkowski, natural solution d7-d6 Lüdenscheid (Muellen’s choice, three moves later) is risky, because it intensifies Black’s weaknesses on the white squares and White’s advantage in space. 5...Bg6 5...Bxc2? 6 Qxc2 fxg5 7 Bd3 +/- [1]. 5...Bxg2 6 Bxg2 fxg5 7 Nh3 Nf6 8 Nxg5 g6 9 Nb5 Bh6 10 h4, and Black is under pressure. 5...Bxd5 6 Nxd5 fxg5 7 Bd3 offers White attacking chances: 7...g6 8 h4 gxh4 (8...e6 9 hxg5 exd5 10 Rxh7 Rxh7 11 Bxg6+ Rf7 12 Bxf7+ Kxf7 13 Qxd5+ Kg7 14 Qxa8 Qe7+ 15 Kf1 Nc6 16 Qc8 +=) 9 Rxh4 Bh6 10 Be4 Nc6 11 Nf3 +=. More precise is 7...Nh6! 8 h4 g4 9 Ne3 g3 10 fxg3 Nc6 11 Qe2 e6 12 0-0-0, but also in this case White has good compensation for the pawn. 6 Be3 6 Bf4 e5 (or 6...c6 7 Qe2) 7 dxe6 dxe6 8 Qf3 c6 (8...Nd7? [1] is met by 9 Bxc7! +-) 9 Bb5 (9 Bxb8 +/=) 9...e5? (9...Ne7 10 Bd3 e5 11 0-0-0) 10 Bxc6+ Nxc6 11 Qxc6+ Kf7 12 Qc4+ Ke8 13 Rd1 Qc8 14 Qb5+ Kf7 +/.

15 Bxe5!? fxe5 (15...Qe6 16 f4 Bh5 17 Nge2) 16 Nf3 Nf6 17 Nxe5+ Ke7 18 0-0 Bf5 19 Rfe1 Be6 20 Nf3 Kf7 21 Rxe6 Bc5 22 Qb3 Kf8 23 Ne5 Qc7 24 Nb5 Qb7 25 Nd6 Qc7 26 Nb5 Qb7 27 Rxf6+ 1:0, J. Tait – J. Derby, Sheffield 1995 [3]. 6...Bf7 7 Qf3 a6 The correct continuation was 8...c6, with chances for both sides. As a rule, when Black avoids this typical move in the Mousetrap Gambit, to question White’s center, he will stand worse. 8 0-0-0 d6 Black finally plays the risky d7-d6, to develop his queen’s knight. He took some precaution (Bf7, a6), but nevertheless the weaknesses on the white squares will count. 9 Nge2 g6 10 Nd4 Nh6 11 g4 Nd7 12 Qh3 Ng8 13 Be2 Qc8 An attractive position for White. f2f4 now would have been best. 14 Qf1?! Bg7? His best chance for counterplay was 14...b5. 15 Rg1 Nc5 16 b4 Nd7 Or 16...e5 17 dxe6 Nxe6 18 Bf3 Ra7 19 Nc6 Ra8 20 Qe2 with a clear advantage for White. 17 f4 Nb8 18 Rg3? (18 Bf3! +/-) 18…Ra7 (18...c5! =) 19 Bg1 c5 20 dxc6 Nxc6 21 Nxc6 Qxc6

22 Nb5! Rd7 23 Rc3 Qb7 24 Nxd6+ exd6 25 Bxa6 Qa7 26 Rc8+ Ke7 27 Re1+ Be6 28 Rxe6+? (28 Qe2 is mate in 3) 28...Kf7 29 Rxd6 Rxd6 30 Qc4+ Re6 31 Rc7+ Qxc7 32 Qxc7+ Ne7 33 Bc4 f5 34 Qd7, Black resigns. In the next game, 4...h6 is an improvement upon 4...f6 from the first example. But without an early c7-c6, White’s piece play still becomes menacing. M. Lütt – M. Ziabari Siegburg 2005 Owen’s Defense [B00] 1 e4 b6 2 d4 Bb7 With hindsight 2...e6 seems wiser, to avoid 3 Bg5. By the way, after 1 d4 b6 White can himself choose another move-order and play 2 Bg5! first. Then 2...Bb7 3 e4 reaches the Mousetrap Gambit by transposition. So the new gambit can have an influence even on the choice of your very first move. Against someone who likes to play Owen’s Defense, beginning with 1 d4 might be best. Black then has to find the precise move-order 1...e6. 3 Bg5 Bxe4 4 d5 h6 4...c6 can lead to positions very similar to the analysis at the end of this article (4...h6 5 Bh4 c6), in most cases a later h6 and Bh4 will lead to a transposition of moves. By playing h6 before c6, Black reduces White’s options. For example, when h6 is played at a later stage, it might have become clearer where White’s bishop stands better, on f4 or h4. And also after 4...c6 White has some additional possibilities like 5 c4 [1] or 5 d6?!. 5 Bh4 The alternative 5 Bf4 has not yet been tested in practice (see analysis below). At first sight it seems less logical, because it allows 5...e6. Conversely, if 5 Bh4 then 5…c6 is critical (see below), the alternative at least should be considered. 5...g5 5...Nf6 seems rather passive: 6 Nc3 Bg6 (6...d6?? 7 Bxf6 +- Kohlhage – file:///C|/cafe/kaissiber/kaissiber.htm (5 of 11) [12/27/2005 11:59:27 AM]

Gehrke, Germany, corr. email 2002) 7 Nf3 c6 8 Ne5 Bh5 9 g4 Qc7 10 Qe2 Bg6 11 Bg2 +/11...Be4 (11...Nxd5 12 Nxd5 cxd5 13 Bg3 +/-) 12 Nxe4 Qxe5 13 Bg3 Qxb2 14 Nd6+ Kd8 15 Nxf7+ Ke8 16 Be5 Qxa1+ 17 Bxa1 Kf7 +-. The material is roughly balanced (Black has rook, knight and pawn for the queen), but White’s position is overwhelming. With the help of his opponent, Black managed to draw the game: 18 dxc6? (18 0-0! wins, Black has no reasonable moves) 18...Nxc6 19 Bxc6 dxc6 20 Qc4+ e6 21 Qxc6 Rc8 22 Qa4 a5 23 Ke2 Bb4 24 a3 Bc3 25 Bxc3 Rxc3 26 h4 Rhc8 27 Rd1 Rxc2+ 28 Rd2 R2c4 29 Qb5 R8c6 30 Rd4 R4c5 31 Qb3 Rc3 32 Qb5 Nd5 33 Kf1 g6 34 g5 h5 35 Re4 R3c5 36 Qb2 Rc1+ 37 Kg2 R1c3, draw, Thoma – Mehlhorn, corr. 1995. 5...c6 is probably best: 6 Nc3 (6 c4? g5 7 Bg3 Bg7 8 Nc3 Bxc3+ 9 bxc3 d6 10 Nf3 Qc8 -/+) 6...cxd5 (6...Bxd5 7 Nxd5 cxd5 8 Qxd5 Nc6 9 0-00, White has enough compensation for the pawn) 7 f3 (or 7 Nxd5 Nc6 8 Ne2 Bxd5 9 Qxd5 Qc8, followed by e6) 7...Bh7 8 Nxd5. It is unclear whether White’s greater piece activity fully compensates for the pawn. This is a kind of gambit, which I’d like to play with White, but I admit this might be a matter of taste. 6 Nc3 6...Bg6 6...Bxc2 7 Qxc2 gxh4 8 Nf3 +=, says Michael Lütt [5]. In my booklet [1] I wrote that White has compensation, indicating that Nf3e5-g6! was one of his threats, and that Black’s king would have difficulties in finding a safe harbor. For example 8...c6 9 0-0-0 Nf6 10 d6! e6 11 Nxh4, with a strong attack. 6...Bxg2 7 Bxg2 gxh4 isn’t better. White can develop quickly, while Black has to find a place for his king. It is no question that such a gambit must be correct. 7 Bg3 Bg7 8 Nf3 d6 

As in the first game, Black decides to weaken the white squares. Here this move has an additional motivation: to prevent Ne5. But still ... the alternatives don’t look too promising either: (a) 8...Bh5 9 Be2 f5?! (9...Bxc3+ 10 bxc3 Nf6 11 Be5 +=) 10 h3 f4 11 Bh2 c6 12 Qd3, and White won in 22 moves, Knorr – Kirste, corr. 1989. 10 Qd3 f4? 11 Ne5 +- seems even stronger (b) 8...Nf6 occurred in four games: 9 Qd2 0-0 10 0-0-0 c6 11 h4 g4 12 Ne5 Bf5 13 Bf4 Kh7 14 Bd3 Bg6 15 Nxg6 fxg6 16 h5 Nxd5 17 hxg6+ Kg8 18 Nxd5 cxd5 19 Bxh6 Be5 20 g7 Rf7 21 Bh7+! and mate in a few moves, 1-0, Erben – Frenzel, corr 1990 (ICCF). 9 Qd2 Ne4 10 Nxe4 Bxe4 11 Be5 Bxe5 12 Nxe5 c6 13 Qd4 cxd5 14 Nc6 dxc6 15 Qxh8+ +-, and Black’s position was hopeless, 1-0, 27, Erben – Antoszkiewicz, corr 1990 (ICCF). 9 Ne5 Bh7 10 Bc4 (stronger is 10 h4!) d6 11 Bb5+ Nfd7 12 Nxd7 Nxd7 13 Bc6 0-0 14 Bxa8 Qxa8 15 0-0 e5 16 f3 f5 17 a4 a6 18 Be1 Nf6 19 Qd2 Re8 20 Bf2 draw, Knorr – Reichel, corr. 1989. 9 Ne5 Be4 10 f3? Bh7 11 Qe2 d6 12 Nc4 0-0 13 0-0-0 c6 14 dxc6 Nxc6 15 Ne3 Rc8 16 Qe1 a5 17 h4 Nb4 18 a3 Rxc3 19 bxc3 Na2+ 20 Kb2 Nxc3 21 Kxc3 Nd5+ 0-1 Knorr – Bangiev, corr. 1993. The only Mousetrap Gambit game that I know which was won by Black. It wasn’t convincing, though, because White has 10 Nxe4 Nxe4 11 Qf3 +/, when both 11...Nd6 12 h4 and 11...Nf6 12 0-0-0 give him a powerful attack. 9 Bb5+ Nd7? 9...c6 10 dxc6 Bxc3+ 11 bxc3 Qc7 had to be tried, according to Michael Lütt [5]. 10 Nd4 Bxd4 11 Qxd4 Ngf6 12 0-0-0

White has full compensation for the sacrificed pawn. Like the game before, Black’s main mistake has been not to play a well-timed c7-c6. 12...a6? “Gives White the one tempo that he needed to start his king-side attack,” Michael Lütt [5]. 13 Bc6 Ra7 14 h4! g4 15 h5 Bf5 16 Qf4 e6 17 Rde1 Kf8 18 Bh4 Kg7 19 f3 Ne5 20 dxe6 fxe6 21 Rxe5! dxe5 22 Qxe5 Black is helpless against the transfer of the white rook to the seventh rank, which finally costs him the knight f6. 22...Rf8 23 Rd1 Qc8 24 Rd7+ Qxd7 25 Bxd7 c5 26 Bc6 Raf7 27 fxg4 Bxg4 28 Ne4 Rd8 29 Bxf6+, Black resigns. Analysis: A Critical Line What can we learn from these practical disasters? One thing emerged quite clearly: Black has to play an early c7-c6, to eliminate White’s basis for his “divide et impera” strategy, his d5-pawn. The following analysis isn’t very detailed, but will give you some hints concerning more critical lines. 1 e4 b6 2 d4 Bb7 3 Bg5 h6 In most cases this will only lead to a transposition of moves. To delay taking on e4, however, might in fact be a slight improvement upon 3...Bxe4. On the other hand, it isn’t surprising that only 3...Bxe4 happened in practice. Seeing that White has squandered a full center pawn, it is difficult to keep calm and watch out for subtle nuances in the move-order. It also makes a difference (in comparison to the first game) whether Black plays 3...f6 at once. Now in [1] my analysis continued: 4 Bf4 Bxe4 (4...e6 5 Nc3 Bb4 [1] 6 Qh5+ g6 7 Qf3 f5 8 Qg3! +=) 5 Nc3 Bb7 (or 5...Bg6 6 Qe2 e6 7 0-0-0 Ne7 8 h4 Bf7 9 g4 etc.). Here the old

analysis 6 Nb5 Na6 7 Qe2 (threatening 8 Bxc7!! Nxc7 9 Nd6 mate) 7...e6 8 0-0-0 Be7 [1] gives White some advantage after 9 Qg4, intending Qg3 and Bc4. But 6...d6 7 d5 c6 [1] seems playable for Black. Fortunately, White has the better move-order 6 Qe2! e6 7 Nb5 Na6 (now d6 isn’t possible) 8 0-0-0 +=. 4 Bh4 4 Bf4!? is an interesting alternative. It’s true that my booklet [1] put a question mark behind the move, because it allowed 4...Bxe4 5 d5 e6 (the pawn is no longer pinned), but after 6 Nc3 the situation isn’t clear. 6...Qf6 (6...Bb4 7 Qd4) 7 dxe6!? 7...dxe6 (after 7...Qxf4?! 8 exf7+ Kxf7 9 Bc4+ Ke8 10. Nge2 Qe5 11 Nxe4 Qxe4 12 Bd5 White wins back more than he has invested) 8 Qg4!? followed by 0-0-0 or Qg3, unclear. So when 5...e6 isn’t the move, we should consider 5...c6 6 Nc3 once again: 6...Bxd5 (6...cxd5 7 f3!? Bh7 8 Nxd5 d6 9 Bb5+) 7 Nxd5 cxd5 8 Qxd5 Nc6 9 0-0-0. White has sufficient compensation for his pawn. The pair of bishops in an open position, plus play against Black’s center pawns. We cannot prove a clear advantage for White, but Black’s position is rather uncomfortable, which justifies the sacrifice of a pawn. He suffers from weaknesses on both wings. Ba6-b7 might be a possibility, and if the d7pawn advances, this weakens the c6-square (Bb5!). And the h6-pawn invites an attack g2-g4-g5. Altogether from a practical perspective, White’s position even seems preferable. 4...Bxe4 Or 4...g5 5 Bg3 Bxe4 6 Be5! Rh7 (6...Nf6? 7 Qe2 d5 8 f3 strangely loses a piece) 7 Nc3 (my old analysis [1] offered the faulty 7 Bd3? Bxg2 8 Qe2, which is refuted by 8...Rg7) 7...Bg6 8 Bd3 e6 9 Bxg6 fxg6 10 Qd3 Ne7 11 Ne4 Nd5 12 c4 Nb4 13 Qf3 +/= [4]. 5 d5 c6!? Instead of 5...g5 6 Nc3, as discussed in the second game (Lütt – Ziabari). 6 Nc3 Bxd5

It is interesting to note the differences between this variation and the analogous position after 4 Bf4, above. For example, after 6...cxd5!? 7 f3 Bh7 8 Nxd5 there is no immediate threat of Nc7+, so Black has time for 8...Nf6. Perhaps 6...cxd5 7 Qe2!? comes into consideration: 7...Nf6 (7...g5 8 Bg3 Bg7 9 Nxe4 dxe4 10 Qxe4 Nc6 11 0-0-0, and Black’s extended pawn chain gives White attacking chances with a later h2-h4. In this line, 8...Nf6? would be too risky because of 9 Nb5) 8 Bxf6 gxf6 9 Nxe4 dxe4 10 Qxe4 Nc6 11 Nf3 e6 12 Bb5, for example 12...f5 13 Qa4 Rc8 (13...Qc7 14 0-0-0 Bg7 15 g4, or 14...a6 15 Bxc6 Qxc6 16 Qd4, or 14...Rc8 15 Ba6 Rd8 16 Rhe1) 14 0-0-0 Qc7 15 c3 Bg7 16 Kb1 (16 g4 Bxc3!?) 0-0?! 17 g4!, and Black is in trouble. 7 Nxd5 cxd5 8 Qxd5 Nc6 9 0-0-0 Black’s straightforward 5...c6 has led to some simplifications, but White still has plenty of pressure along the central files. Whether Black plays g7-g5 or Nf6 Bxf6 gxf6, in both cases White will have targets for his attack. I wouldn’t hesitate to play White in the diagrammed position. For example: 9...Rc8 (9...e6 10 Bxd8 exd5 11 Bh4 +=) 10 Nf3 Nf6 11 Bxf6 gxf6 12 Bb5 e6 13 Qh5! Qe7 (13...Bg7 14 Nd4! Nxd4 15 Rxd4 Rc5 16 Qe2 +=) 14 Rhe1 Qc5 15 Rd5 Qxf2 16 Re2 Qxe2 17 Bxe2 exd5 18 Qxd5 +/-. Sources: [1] Stefan Bücker: Das Naselwaus, in: Gambit 59, Nuremberg 1984 [2] Eric Schiller: Unorthodox Chess Openings, New York 1998 [3] Stefan Bücker: (two games) in Kaissiber 7 (1998), p 73. [4] Stefan Bücker: (reply to letter by Rolf Spoerri) in Kaissiber 8 (1998), p 4f. [5] Michael Lütt: (game commentary) in Kaissiber 21 (2005), p 5.

Very long, but I understand the gambit now!

Glad that you took something from it! This text is originally from Stephen Bucker's blog, which is long deleted, and only available on archive sites now. To check out his complete article about many other unorthodox openings, check out this link:

https://pdfcoffee.com/s-bcker-amp-c-galofre-chess-cafe-over-the-horizons-1-74-pdf-free.html

What's his rating?

Here he is:

https://www.365chess.com/players/Stefan_Buecker

https://de.wikipedia.org/wiki/Stefan_B%C3%BCcker

Ok