I apologize, it looks like I found a flaw in my analysis. In order for this trap to still work, white must play 5. h3 to make the bishop to move to h5 where it cannot defend the d7 square. The moves should go 4. Bg4 5. h3 Bh5 6. O-O, and then 6. Ne5 or 6. Nf6 7. Re1 Ne5, where the trap will work.
The theme of the trap has been well known for more than a decade. I don't know how familiar are the typical Kopec opening players with it . In general it is called Legal's trap or Legal's sacrifice even though in the original Legal's sacrifice you mate with a bishop on f7 and in this version you win material with a bishop check on b5. In my opinion one should seperate these two versions by naming, too., but as I said I am not aware of a seperate name. Maybe somebody knows it. Renaud and Kahn gave 4 aspects of Legal's pseudo- sacrifice in their book 'L' art de faire mat' without trying to give seperate names, at least.
Here an old game by Mieses in the Center game with ths trap:
And here a game in Queens Pawn opening:
Of course ,one should mention this old opening trap in the Queens Gambit declined where black sets the trap with colour reversed by winning back the queen with B b4+ and remains a piece up.
By the way in refrence to your analysis: I don't think you necessarily have to insert h3, because even if your opponent captures your knight with d*Ne5 after Bb5+ and Bd7 you can play Be2 and migt have a positional advantage because of the better pawn structure. I am only a patzer and might be wrong but the engine agrees.
Here is an old game by Tarrasch against Chigorin with the Legal's sacrifice which has again a different follow-up. (Of course there is also the pin break of the knight after sacrificing a bishop on f7 to capture the bishop on g4 afterwards. )
And the following is a very deep version of Legal's sacrifice which isn' t easy even for strong current grandmasters to spot although Kurt Richter gives a correspondence game from 1922 where Dr. Imbaud played 9. N *e5 against Strumilo in the same position. In the Scotish opening there is a mirrowed version ( with the exeption of a queenside pawn move by white) of it which was overlooked by GMs.
I've often play this sytem as white, nobody played Bg4, even at "low" level...
Ne5 is not really falling into a trap (white didnt et a trap, it is black who only creates it) : it is a bad move even if white doesn't have Nxe5.
Ne5 doesnt develop black kingside, and white could consider Bb5, Qa4, Be2 are viable moves with a better position anyway
@MasonLasker: Those are some really great games, thanks for sharing. I noticed it was very similar to the Legal Trap in the Philidor Defense. That's how I got the idea to play Nxe5.
@IM poucin: I'm surprised nobody plays Bg4 against you. I see it pretty frequently, and a CM played it against me last night (granted, it was a blitz game). But in his YouTube videos IM Kopec recommends that white play an early h3 to block the bishop from coming to g4. He must have seen it in a lot of his games. And yes, I agree it is black who "creates" the trap, but are there really any opening traps that don't start with a bad move from the other side? I think that especially at the lower level Ne5 would look like a very logical move.
@MasonLasker: Those are some really great games, thanks for sharing. I noticed it was very similar to the Legal Trap in the Philidor Defense. That's how I got the idea to play Nxe5.
@IM poucin: I'm surprised nobody plays Bg4 against you. I see it pretty frequently, and a CM played it against me last night (granted, it was a blitz game). But in his YouTube videos IM Kopec recommends that white play an early h3 to block the bishop from coming to g4. He must have seen it in a lot of his games. And yes, I agree it is black who "creates" the trap, but are there really any opening traps that don't start with a bad move from the other side? I think that especially at the lower level Ne5 would look like a very logical move.
Bg4 is not so annoying for white who can play h3-g4 to unpin.
It is true that i almost play the move order 1.e4 c5 2.Nf3 d6 3.c3 Nf6 4.h3 which prevents Bg4 but even with 4.Bd3 I don't remember facing Bg4.
I also played 4.Be2 which is another choice, but then u can say good bye to the Legal's mate trap (which never happens as I said but we have another trap with 4.Be2 Nxe4??), and here it is white who sets it).
Anyway, if u play Bd3 system, the advantage playing h3 first is that u remove Bg4 option, so cannot be bad for white...
I've been playing the Kopec System against the Sicilian recently, as I was looking for something that people would not be expecting, but is still sound. It's named after IM Danny Kopec, who actually passed away not too long ago, on June 12, 2016. He made videos for his opening that are still available on YouTube. The opening looks very strange, but the positions it can give white often share similarities to the Ruy Lopez, and it can be very strong.
Anyways, recently I discovered an opening trap that has now arisen on three separate occasions, twice in blitz games here on chess.com, and once over the board at the Illinois Open (my opponent there saw it and prevented it). Just wondering if anyone else has seen this trap before, or seen a trap like it, and if it already has a name?