Chess Opening Theory/1. e4/1...e5/2. f4/2...exf4/3. Nf3/3...g5/4. h4/4...g4/5. Ne5/5...d6/6. Nxg4/6...Be7

White's h-pawn is doomed. The only move that saves it is 7.h5, but there's a subtle problem with that move. Black has the secondary threat that after 7...Bh4+ 8.Nf2 Nh6, the next move is going to be ...Ng4 winning the pinned knight on f2 (or at least forcing the h1-rook to sacrifice itself for the bishop). If the White pawn were not on h5, White could offer some defence with 9.Qh5, chasing the pinning bishop away before the knight arrives on the scene.

Doing nothing at all would be a better move than 7.h5, but that's not allowed, so how could White make some use of this spare tempo?

You can postpone the decision one move with 7. Nf2, like Baron von Heydebrand und der Lasa did against Staunton, but there's no reason for Black to do anything other than grab the h4-pawn and transpose to one of the lines below.

7. d4 and 7. d3 threaten Bxf4, followed by g3 getting out of the pin. 7.d3 may be overly cautious compared to 7.d4, since there's no imminent threat to e4 whereas keeping the Black queen's knight out of e5 is very useful, especially if White's going to put a queen on f3 to help defend the kingside.

7. Bc4 is certainly in the spirit of the King's Gambit, making a bolt-hole on f1 for the king. But in this line, the king doesn't want to be on f1 particularly. 7...Bxh4+ 8.Kf1 Qg5 9.Nh2 Qg3 threatens mate in one and, although 10.Qe2 Nc6 11.Nf3 keeps everything nailed down for now, White isn't exactly happy being material down and being made to man the barricades while Black develops pieces.

7. Qf3 is the no-nonsense approach, aiming to round up the forward f-pawn. After 7...Bxh4+ 8.Nf2 Black can resist with either 8...Bg3 or 8...Qg5, and White can add a second attacker with 9.d4 which transposes to the 7.d4 lines.