3... Qxd5 seems to lead to a slower developement after 4. Nc3, Qa5, 5. Bc4, and black has to find a good developement plan for his lsb (5... Bg4? 6. Bxf7+, KxB, 7. QxBg4, threatening Qe6+). Would it lead somewhere for black?

@damalfi: I don't think I would dare play this line for Black!

exd4 should also be considered

4... exd4 is really funny for tactical play: say white takes with the N (5. Nxd4), black has ...Bc4. White can protect with Nc3, or try a more aggressive and tricky line with 5. Nb5 (with the terrible Nxc7+ threat). Black can defend with Na6, but his position is not very promising. Can black get something more? 5. ...Qf6?! threats mate in f2, so white couldn't cash the Ra8 after the forking Nxc7+. But white has plenty of ways to stop the mate in f2, being one of them, 6. Qe2+. Black will simply parry it with Ne7, giving time to white to cash the fork: 7. Nxc7+, Kd8 (the idea is to chase the N and make room for Re8 very soon), and if white dares 8. NxRa8, black has Re8, with a very enjoyable position for tactics: Even after Be3 and the B's exchanges, black has chahces for a lucky combination to equalize, and the Na8 is a credit card.

I think after 4...exd4. I'd be more inclined to play 5.Qxd4. Something to think about, I guess!

white is just enticing f5, after which the question will be is white correct that the pawns on e4 and f5 are attackable weaknesses or are they the spearhead of blacks devasting attack. It is unclear at this point

Of course, one wonders the downsides of Ng5... a long taks for now! Wonderful game...

Can't white plan g3, Qe2, Bg2 to minimize black's pawns effect?

here, Joe, the doubled pawns are good for white. Apart from being incurred when White took the d-pawn, they control squares that Black really would rather they were not under White's control.

6 Bb5 seems less thematic and more lower rated player wants to trade off a piece against a higher rated player. It's not clear yet whether white will need his LSB or not.

In my view, the more cramped player here is black, so white shouldn't exchange. Exchanges relieve the "squeezed one". White could have been interested in Qe2, so to provoke Ne7 (otherwise, white can take advantage of the pin on e4 to develop Nc3-g4, threatening to land on e6). This will keep white a little ahead, with lot of possible lines to go for.

BQ has only one apparent purpose here: Qb5, blocking white's castling and threatening Qxb2 once the Wdsb moves. Not great prospects, as both "threats" are easily met by white with good developement moves. I don't see a future for that. Therefore, BQ could have been more useful on the e column (Qe7), leaving room for Nf6, or just where it was, considering for later the kamikaze Qg5, and if Nxe4 (BQ is threatened), Qxg2! (yahooo!!!).

In my view the exchange was good for White, as his King's bishop didn't really have a good square in this position. Black is somewhat relieved of the problem about what to do with his light-square counterpart, sure. So both sides had reason to be satisfied with the bargain.

Black's last move refutation. Black has no attack plan here from the possible ones (pushing his pawns and press on the e column, taking advantage of a certain weakness on e3, OR forcing white to defend his naked kingside with Qg4, etc.

That the engine makes mistakes is generally due to the 'horizon effect' - a problem that has beset chess engines from time out of mind. But for short range tactics, they can usually be relied upon.

At most a slight inaccuracy, nothing fatal

This becomes very tactical. Willingly or not, white has applied an uncommon but sound strategy: "if W takes, black will free his B, pinning my f pawn... no good. Can I avoid that? No, but I can just let him take it, and his B will not be pinning my f pawn, so I will be able to play it". And why would W want to play the f3 pawn, weakening the ds diagonal? Because, in return, he will have broken black's pawns and got the possibility to exploit Q or R e1 to pin the e pawn...

It is interesting that both d-pawns are passed. You don't see that very often... ++++ @damalfi: After 10...e3 11.Nb6 f4 12.dxc5 Be5!? 13.Qd3, White threatens at least to pick up four pawns for the piece, or three pawns for the exchange, after 14.Bxe3!?

10... e3 looks interesting, too. White has 1) 11. Nb3, which seems best. Only counterside is f4 by black, at the cost of the c5 square and more white's penetration with his own pawns. 2) Use the pin, with 11. Re1, or Qe2, in both cases allowing cxd4 (and black is the one who has an impressive center!). Do I miss something? ++++ @arckduke_piccolo: you are probably right, but I still see after your line black has 13... Nc6, taking advantage from the pin, which allows Bxb2 and Nb4. Maybe black can get out even from the exchanges, but if 14. Nc3? (instead of Bxe3), Nb4, and the WQ has to go to e2, (15. Qe2), and here black has BxNc3, or maybe better Qf5. giving support to Nc2-Nd4.

I'll look to 11... Ng4 instead. Black threats h2 and e3. The normal 12. Nf3 doesn't work because of fxe4 (white can counter with 13. Qe2, with very nice tactics from both sides, thoug), or choose among 12. exf5 (exploiting the e column) or 12. Rxf5 (preventig black's castling and invading black strongly), allowing black the choice to play Bxh2+ (a dead end?) or go for the "fork-pin line", that could be something like: 12. (say) exf5, Ne3, 13. Qe2, o-o, reaching this "hard to assess" position!

@damalfi: You know: I think you are on to something. I don't recall that 11...Ng4 crossed my mind in this position, or if it did, I didn't stop to think about it. I had planned upon ...fxe4 ahead of time and stayed with it. But the line: 11...Ng4! 12.Nb3! Bxh2ch 13.Kh1 Qe8! (threatening ...Qh5) 14.Qf3 Bd6 15.Bf4 Bxf4 16.Qxf4 Qh5ch, with ...Rf6 to come, seems to offer Black a very promising game. That was an opportunity missed!

The other choice could have been to let white take it and try to get something from the resulting diagonal against white's king. It fails because of 12... b6, 13. Qxd4! and black can't use Bc5 because of NxB, bxN and black has nothing. BUT, black can try 12... Na6, and after (say) 13. Qxd4, (Nxd4 leads to Bc5, Be3, not defended... looks dangerous), Nb4!, threatening the fork Nc2, and landing on d3... with Be5 in sight, and possibly o-o!... not all that bad!

@damalfi: I'm not sure that line will work, on account of, e.g. 12.Nb3 Na6?! 13.Qxd4 Nb4 14. Rxf6 and now [A] 14...Nc2 15. Qxe4+ Kd8 16. Rxd6 Qxd6 17. Qxc2 or [B] 14...gxf6 15.Qxe4ch Be5 16.a3 Na6 17.Bf4 with two pawns for the exchange and an active game.

Something has to be made about the threat BxN, gxB, Rxf6, winning a pawn and penetrating into black's field a lot. Here, the natural option seems Be4, that incidentally threats Bxb2, and Bd4+ if Nb3 moves anywhere. The counterside, Nc5, shall be met with great care and danger for black, leading to this: (13. Bg5, Be5, 14. Nc5, Qe7, 15. Qa5+, Kf7!?) It seems weird, against the natural Nb-d7, but it would have meant to allow Nxb7... the Kf7 move self-pins the Nf6, true, but leaves black the inmediate threat Bd4+, BxNc5, AND Bxb2, winning an exchange...

WQ is looking dangerously to black's kingside! Black's Nf6 will be exchanged, after which the WQ will be able to penetrate. Qg4 could be a way to release the pressure and solve the weird BQ's position.

Things are not looking good for Black's chances.

the potential pawn roller must be maintained

Maybe it is too easy to say it now, but it seems that black's prospects lay into equalizing the Q's factor, OR into exploit the Na6-Ng4-Nc2 route. The support purpose of this move could have been accomplished by the Q (Qe7) without losing control of f6. In adition, c5 would have been held.

@damalfi: You are right about that, and the notion kept coming to mind. It was really a matter of timing, and I have to admit, in this game my sense of timing was a bit off. At this point I was reluctant to play ...Na6 on account of the need to support my advanced pawns. I had much rather lose a flank pawn (here) than an central one, even at the price of weakening my King position...

Be5 is a triky move now, as if Nxe4 (thinking that BxR, NxB+), black has Bxh2+, KxB, RxNf4, incidentally protecting from Qf4+, so black's Q can finallo move somewhere else!