If it was a movie, it'd be "ECO A01, Larsen's Opening: the horror of unconventional first moves." I'd probably rent it, but I'm not sure I'd go to the cinema to see it...

Yeah it is downright rude   Well, I guess you can always abort the game if you don't want to play, or you can use the opening database to relieve the pain.

I don't really agree: 2...d6 is playable if the aim is to slow down the game; someone who plays odd openings is unlikely to want the game reduced to a slog, I suppose.

I go with jfxleigh, here. I've played 2...d6 myself on GK. But it seems likely that 2...f6 is even better, making sure that the b2-bishop is biting on really hard granite...

Agreed. 3...e4 seems inconsistent with 2...d6

Another idea is 3...f5.

Did white consider 4. d3 exd3 5. Bxd3 ? It removes the annoying pawn and gets development going again...

Castling on opposite sides of the board. Often foreshadows double-edged positions with both sides attacking. Will it be so here? Maybe White has the head start here...

Black was faced with a very difficult decision already, methinks. 9...b5 10.g5 looks pretty good for White, and 9...d5 10.g5 Ne8 11.h4!? with a pawn storm imminent. Black's choice seems reasonable.

Agreed - this is weakening. 10. d5 is also good.

Black's 11th is weakening and cramping at the same time. It also offers White a target, as the annotator indicates. I rather like 11...Nde5, attacking White's g-pawn. If 12.Nxe5 Nxe5 attacks both White's K-side pawns.

White missed 12. Qc4+ Kh8 13. Be2 Nb6 14. Qd3, which might have been quicker.

One suspects that Black assumed White would exchange on e5 - or maybe he wanted to discourage the exchange? Otherwise it's hard to see why Black preferred 12...Nce5 over 12...Nde5. Despite the weakness along the a2-g8 diagonal, Black wouldn't have been too badly placed after the latter move.

18...Ne5 19. Qg2 Nxd3+ 20. cxd3 and white's king suddenly looks less happy. The alternative 18...Ne5 19. Qe2 c5 20. Nf3 Be6 is OK, too.

There's something to be said for 18...Bf6, too.

19. Nxd5?? Qxd5 20. e4 Qd7 leaves black level. But black having missed 19...Qxd5, white then misses 20. Nxf6, which, as the annotator says, would have been winning. L'esprit d'escalier...

The position has become very complicated in the light of the situation along the long dark diagonal. After 19.Nxd5 Qxd5 20.Qxd5 Nxd5 21.Ne6+ doesn't seem to be enough: Black retains 2 knights for the rook. After the suggested 20.e4 Qd7 White keeps some attack with 21.Ne6+ (21.Nxf5+ looks less good) ...Kg8 (or 21...Nf6 22.Nxf8 when Black will hesitate before taking on f8 on account of 23.Bxf6+) 22.Nxf8 Bxf8 (or ...Kxf8) 23.exf5 and White has a very powerful attack by the look of it. What happens in this line if Black takes on e4? Thus: 19.Nxd5 Qxd5 20.e4 fxe4 21.Qxf8+!! Bxf8 22.Rxf8+ Kg7 23.Ne6++ Kh6 24.Bg7+ Kh5 25.Nf4#. Far out.

Hoping to exploit a pin on the d-file perhaps after 24.dxc6e.p. bxc6...? Black is beginning to develop threats of his own...

Agreed! 27...c4 is the only move here.

Worried by 30. Qxc5, maybe? Although 29...Qf6 30. Qxc5 Bb7 is playable.

But after 29...Qf6 30.Qxc5 still looks good: 30...Bb7 31.hxg6 hxg6 32.Ng5!? (or 32.Ne4) and if 32...Qxg5 33.Qc7+ Rf7 34.Rh7+ Kxh7 35.Qxf7+ Kh6 36.Rh1+ Qh5 37.Rxh5+ Kxh5 38.Qxb7 etc. If Black doesn't take on g4, then, say, 32...Rac8 33.Ne6+ or 32....Kg8 33.Qc7.

Another idea (that admittedly I haven't tested) is 30...f4, hoping to develop the bishop on f5.