English, rather.

2 ...e5 & 2. ...c5 would transpose to the English, 2. ...d5 to the Reti. After 2. c4 it's too early to denote the opening path.

Transposing into a Grünfeld.

A poor version of it. In the Grunfeld proper Nc3 rather than Nf3 would have been played. White can now bump the queen with tempo (after 4. ...Qxd5 5. Nc3) or the knight with tempo (4. ...Nxd5 5. e4) since there is no knight on c3 to trade the Grunfeld knight with, as in the Exchange Variation. Black should just transpose to standard KID (3. ...d6) or Benoni (3. ...c5) lines, particularly the later since the dangerous Flick-Knife and Four Pawns Attack versions have been ruled out with Nf3.

Isn't this just bad?

We could be charitable and call it ... provocative. It's not fatally bad.

And the retirement of th queen on d6... also bad. Probably black is trusting on the rate difference... a strong mistake, speaking about pawnstar, that is rapidly developing an aggressive style, looking for good and not "just plain" moves... as he demostrates here.

I agree: the Queen ought probably ought to have gone to a5 or d8. Te latter constitutes a loss of a couple of tempi, but look at the consequence of 4...Nxd5: the knight settles on b6 if Black doesn't want to incur as great a loss of time.

White has an extreme space advantage!

Still, I'd like to play 7. Bd3 to get even more ahead of development, then bump the queen, or castle and break the pin, and black is in a world of trouble already. Might even be worth sacrificing a pawn, if say black follows up with 7. Bd3 Nc6 8. O-O Nxd4 9. e5, to follow with 10. Nd5, perhaps.

Probably it was not necessary to offer queen's exchange so early, since white has a good position. Still, is interesting the concept behind this: if black goes hungry for a pawn, he will become even more behind in developement. This is an advanced concept for a 1550 player...

Also interesting, and in my view best, is offering the "poison pawn" with 7. Bd2. Black can't take the pawn Qxb2 8. Rb1 Qa3 9. Nb5 Qxa2 10. Nxc7+ and a rook drops. Meanwhile Black has to watch for discovered attacks on the queen, for instance Bg7 8. Nd5. So Qb6 is virtually forced. Then comes 8. e5 and Black is not able to move the knight because of similar combinations, ie Nh5 9. Nd5 Qc6 10. Bb5!! which wins queen for bishop. Basically Black is virtually lost in this position. 7. Qa4+?? lets Black off the hook and drops a pawn also.

I don't agree, with Nuntar. Black is playing carelessly.

and white isn't? What is so horrible about Nd6? It keeps an eye on vital central squares and doesn't block the lovely long dark squared diagonal for the bishop, which will move to g7 shortly. Black is just a clear pawn up now.

Not really a 'free tempo': White has paid a pawn for it! In my view the retreat to d6 is quite reasonable: blockading (at a remove) White's isolated d-pawn. Though it's true White has a lead in time and space, but his pieces are somewhat scattered and ill-coordinated. The race is on as Black will (no doubt) try to catch up time, and White organises some operation to take advantage of his (temporary) lead.

I think 9. ...Nd6 has be preferred to unimpede the fianchettoed bishop's range on g7, and block an attack on his c-pawn via Bf4. This defensive post is strong; centralized and protected by pawns on e7 and c7, especially since it can't be prodded away since white doesn't have a c or e-pawn. With careful play black could survive the lagging development and consolidate his position a pawn up, since white's knight is misplaced on a4.

White's knight is misplaced, but not so badly. It can easily relocate not only to c3, but even to c5 (and if b6, Ne4). But the developement is consolidated to 4 to 1 minor piece... a clear edge for white.

c6 does nothing to help black to catch up with developement.

I would seriously have considered 12...Nd5 in response to this move.

In my opinion Black is better here being a pawn up (a central one) and the pawn on d4 isolated. It doesn't seem to me that the dynamic compensation is enough. Black might think about castling now. 12...0-0 and if 13.Rxe7?! then 13...Ne5 attacking both rook and bishop, 14.Re4 Bf5. 12...e6 is instead horrible.

Accurate: white can avoid black's castling, and goes for it! Edit: ok, you're right, white's move didn't avoid black castling but... it does, anyway!

Black's LSB isn't having a great time....

he ought to have played Be6 instead of e6 here...

Although after 12. ...Be6 13. Ng5 is strong, and if the bishop retreats, 14. Bc4 to hit black's weak f7 spot.

White's overwhelming developement runs the game.

12....Nd4 looks best to me, and black is still better than white. After 12.... e6 13. Be6 I think Bf8 is best and the position is even. There is even a line leading to a repetition of moves - 13. Bd6 Bf8 14. Bf4 Be7 15. Bh6 Bf8 16. Bf4 etc

I think Charles means 12...Nd5, the move I suggested in my previous comment. Sure, it means a further loss of time, but then White has to do something about his DSB - which in turn may mean a loss of time for him. After 13.Bg3 0-0 seems safe enough. Doea Black really stand better after 12...Nd5? That might be a matter of opinion, but I'll say this: White will have to play very energetically and well in the short term, because with the extra pawn and the superior structure into the bargain, Black has much the better long-term prospects.

Even better, maybe, 12...0-0 (see my comment on previous move)

As said, white knight wasn't so badly misplaced, after all  

But white is a pawn down, and it is debateable whether or not he should be encouraging exchanges. After 14..... Nxc5, 15. dxc5, Nd5 and there is nothing for white on the d file. Black would be better, white would not have enough compensation for the pawn.

Sometimes exchanges have to be accepted - even brought on - if one wants to make progress. White alternative has White at the moment? The only thing I can think of is minority attack beginning with b4 and Rab1. Another idea might have been 14.Ne5, with much the same idea, but planning to strinke at Black's centre, whilst allowing Black a Q-side majority. All this suggests that White's advantage is more ephemeral than it appears.

Black is thinking too mechanically here. He should play 14. ...Bf8 to shoo away and force white to sac a second pawn, or exchange the offending bishop. He doesn't need to castle. In fact, his king will probably be needed in the center for defense.

I agree. Black should be very careful, and he is not.

I can see White getting a scary hold on the e-file after this sacrifice - I'd call that good compensation, but White is already a pawn down so there is risk here

Black's position, and indeed his play, is so passive white is justified. I could see Morphy or any master doing it in a simul.

Pretty a compliment for Pawnstar, but well deserved. Yes, this is a good sac, even if it is just a pawn for a piece (since white is already a pawn down).

Given the lack of Queens, this is a bold decision!