The position after the 15th move in the following game is worth a close examination. It is clear that White has gotten enough in return for his material sacrifices, but the compensation is not in terms of a loose or hanging piece that will soon be scooped up - it is in the unrelenting pressure on the Black King. But, does he have more than an even game?
Anonymous - Anonymous
5 5 blitz, lichess.org. 2020
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+
4...Kxf7 5.Nxe5+ Nxe5 6.Qh5+ Ng6
7.Qd5+ Kf8 8.Qxc5+ d6 9.Qe3 Qe7
10.Nc3 c6
A recent alternative, also designed to keep White's Knight out of d5: 10...Nf6 11.O-O Kf7 12.d4 c6 13.f4 Re8 14.e5 Ng4 15.Qf3 Nh6 16.f5 Bxf5 17.g4 Nxg4 18.Qxg4 Kg8 19.Rxf5 dxe5 20.Bg5 Qe6 21.Re1 Rad8 22.Bxd8 Rxd8 23.dxe5 Rd2 24.h4 Rxc2 25.h5 Nf8 26.Rxf8+ Black resigned, odoaker2015 - Marienkaefer24h, lichess.org, 2020.
11.f4 a6 12.O-O Nf6 13.e5
White is in a hurry, otherwise he could have gotten in 13.d4, first.
13...dxe5 14.fxe5 Nxe5 15.b3 Ned7
This is a very interesting Jerome Gambit position. Black has an extra piece, White has an extra pawn. Black's King is unsafe, however, and there is the typical defensive flaw: his Knight blocks his Bishop, which, in turn, blocks in his Rook. White's development is much more effective.
What can the first player do? First, there is the decoy sacrifice, 16.Ba3!?. After 16...Qxa3 17.Rae1 g6 18.Ne4 Kg7 19.Nxf6 Nxf6 20.Rxf6!? Rf8 21.Rxf8 Qxf8 22.Qd4+ Kg8 23.Qc4+ Kg7 24.Qd4+White forces a draw by repetition.
If Black is unhappy with this outcome, he can play 17...Qc5, and, after 18.d4 Qh5, 19.Qe7+ Kg8 20.Rxf6!? gxf6 21.Re3 he will see that his opponent has full compensation for his sacrificed Bishop and Rook, and Black will have to sue for peace, himself, with 21...Qd1+ 22.Kf2 Qxc3+ 23.Kg1Qb1+ 24.Kf2 Qc2+, etc.
White could also try something a little less flashy, say 16.Ne4 Kf7 17.Bb2 Re8 18.Rae1, but after 18...Qxe4 19.Qxe4 Rxe4 20.Rxe4 his Rook and pawn would balance out Black's 2 Knights, for an even game.
All of which probably at least partially explains the move White chose, which may not have been as powerful, but was easy to understand.
16.Qf3 h6 17.a4
The Bishop would like to go to a3, without sacrificing itself. The calm move seems to have misled Black.
17...Rg8 18.Ba3 c5 19.d4
Hitting the pinned pawn at c5. As in the notes above, 19.Rae1 was quite powerful.
19...b6
It is time to recall that this is a 5-minute blitz game.
20.a5
Undermining the pinned c-pawn.
20...Rb8 21.axb6 Nxb6 22.Bxc5 Qxc5 23.dxc5 Nbd7
White's plan to win the Queen has succeeded.
24.b4 Rxb4 25.Qc6 Rb8 26.Qd6+ Kf7 27.c6 Kg6 28.cxd7 Bxd7
29.Rxf6+ gxf6 30.Qxd7
The rest is mopping up.
31...Rbd8 31.Qg4+ Kh7 32.Qf5+ Rg6 33.Rxa6 Rdg8 34.Ra7+ Kh8 35.g3 R8g7 36.Rxg7 Kxg7 37.Nd5 Rg5 38.Qd7+ Kg6 39.c4 h5 40.c5 Rxd5 41.Qxd5 f5 42.c6 Kg5 43.c7 h4 44.gxh4+ Kxh4 45.c8=Q f4 46.Qcg8 Black left the game
White has enough time to be sure he avoids stalemate.