Jens' "Wild Moody Swings"
Jens starts out with a significant advantage, but he senses it slipping away - thus generating the mood swings he refers to. What isn't so clear from his notes is a sense of where and how he starts to let his opponent off the hook, and that's where I think I can offer a useful contribution.
1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Nxe4 6.d4 b5 7.Bb3 Be7 8.Nxe5 Nxe5 9.dxe5 Bb7 10.Bd5 Nc5? 11.Bxb7 Nxb7 12.Qg4 g6 13.Nc3 O-O 14.Bh6 Re8 15.Rad1 Nc5
Here Jens played 16.f4, and after 16...b4 17.Nd5 c6 his advantage remains, but to some extent the position has gotten out of control - Black has more defensive resources than the diagram position suggests he deserves.
The idea of playing f4-f5 is a good one, and if we can combine it with pressure against d7, prevent ...b4 and even make the f4-f5 idea come with gain of tempo, then we'll have found a good solution. Therefore, the strongest continuation is
This prevents ...b4 and forces the Black knight to e6 (otherwise Rxd7 is crushing).
And now the threat of 18.f5 is a big problem for Black. Let's look at three possibilities:
(A) 17...Bxb4 18.Ne4
Threatening 19.Nf6+ and 19.f5, where the latter not only exploits the pin but opens the 4th rank, so that a subsequent Nf6 would discover an attack by the queen on the Bb4.
18...Kh8 19.Nf6 Bc5+ 20.Kh1 and if 20...Re7 (to prevent both 21.Nxe8 and 21.Rxd7), 21.Qh4 wins, as there is no good defense to 22.Bg7+ followed by 23.Qxh7+ and 24.Qg8#
(B) 17...Bf8 18.Bxf8 Nxf8 19.Nd5 Re6 20.Nf6+ with a winning positional advantage.
(C) 17...f5 18.exf6 Bxf6 19.Ne4 (threatening 20.Rxd7 Qxd7 21.Nxf6+) d5 20.f5 Ng7 21.Nc5 Qd6 22.fxg6 hxg6 23.Qf3 wins a pawn while continuing to have a large positional advantage.
16.b4 is one of those moves that's obviously right when you see it, but the tough part is thinking of the move in the first place. After all, White's initiative is in the center and on the kingside, so why even consider a move like b4? The main reason is to ensure a promising future for White's knight: d5 is a wonderful square, but it's unstable, as it can be kicked with ...c6 - which is what happened in the game. That leaves e4, but the Black Nc5 stops it. Furthermore, the Black knight is well-placed on c5, but vulnerable to attack on e6. Put the two ideas together, just thinking of the logic of the situation, and out comes 16.b4!
In sum, there's an art to attacking chess, but it's remarkable how much we can discover just by thinking through the needs of the position and ensuring the activity of all our pieces.