Food For Thought

MY one loss at Newmarket came in round two as White in a Veresov that began 1.Nc3 d5 2.d4 Nf6 3.Bg5 Nbd7 4.e3 - somewhat insipid stuff, at least by White.
Quite a few players are reluctant to play 1...d5 in this sequence because they are uncomfortable against what is by far White's most popular second move here, ie 2.e4!?
The mainline after 2...d4 runs 3.Nce2 e5 4.Ng3. The first person to have apparently reached this position as White was Lasker, albeit in a simul. One idea in the position is that Black's set-up is ripe for the pawn-lever f4, which Lasker did indeed play in the game (Lasker - Ewers, 1909).
Black's main alternative to pushing on with 2...d4 is to exchange with 2...dxe4. After 3.Nxe4, White can claim he has gained a tempo (it is Black to move, but only White has tempi on the board - N-c3-e4).
In a handful of games, including a win by 2300 over a 2370, Black has tried to punish White with the extravagant  3...f5!?, intending to meet 4.Nc3 or 4.Ng5 with 4...e5!? A word of warning - my main analysis engines, Stockfish10 and Komodo9, are not impressed with Black's play. On the other hand, engines are not very reliable in many early-opening positions.
Supposing, however, White is not happy with the lines after 2.e4!? (and wants to avoid the familiar lines starting with 2.d4)?
One possibility is 2.e3. After 2...e5, White can try 3.d4, when he is playing a French Defence with colours reversed and an extra tempo.
His extra tempo (the move Nc3) is not bad - after all, in the French proper, after 1.e4 e6 2.d4 d5 3.Nc3, one option for Black is 3...Nc6!? Carlsen is among strong players who have tried it, albeit, in his case, as far as I know, only in a rapid game.
One "problem" with this is that after 1.Nc3 d5 2.e3 e5 3.d4 (3.Qh5!? is worth investigating), Black can reply 3...exd4, when 4.exd4 transposes to a French Exchange that is more usually reached via 1.e4 e6 2.d4 d5 3.exd5 exd5 4.Nc3. In this sequence the moves 4.Bd3 and 4.Nf3 are much more popular (and arguably more flexible).
However, instead of 4.exd4, White can get on with development with 4.Qxd4!?, threatening Black's d pawn.
The most natural defence is 4...Nf6, after which 5.Nf3 Nc6 6.Bb5 Bd7 7.Bxc6 Bxc6 looks absolutely fine for Black, although Stockfish10 likes 8.b3 for White.
This last line is not very forcing. Indeed, White can vary right at the start with 5.e4!? My idea is that if Black wins a pawn, and holds on to it, with 5...dxe4 6.Qxd8+ Kxd8 7.Bg5 Bf5, White gets good compensation with 8.0-0-0+ (the engines reckon 8.Bc4 is even better).
You might think this is getting a bit far-fetched - I know I did when I was musing on it earlier this evening. So imagine my surprise when I checked the lines with ChessBase's 2019 Mega database and found 5.e4!? was played in Nimzowitsch - Tarrasch, Bad Kissingen 1928.
Tarrasch did not try to win a pawn, preferring 5...Nc6.
The game continued: 6.Bb5 Bd7 7.Bxc6 Bxc6 8.e5 Ne4 9.Nxe4 dxe4 10.Ne2 Be7 11.Be3 Qxd4 12.Nxd4 Bd7.

Position after Black preserved the bishop-pair with 12...Bc6-d7

Black has the bishop-pair but Nimzowitsch went on to positionally outplay his great rival, with Tarrasch suffering the embarrassment of losing an opposite-coloured bishops ending that I suspect many people would instinctively regard, at first sight, as being rather drawish (whether it really should have been drawn is another matter).