The fact that 2.Nf3 is not only the most played but also the most recommended second move after 1.e4 Nc6 ennobles The Dark Knight System as a serious opening. According to this, the consequent occupation of the centre with 2.d4 is connected with so many imponderables and risks that White should step back from this and go for 2… e5 with a move transposition into classical King’s pawn openings.
From Black’s point of view there is nothing to object to in principle. One may play 2… e5 and thus free his classical opening preparation from King’s and middle gambit, Vienna game etc.
Even better, however, is that Black has more options, of which I consider 2… d5 and 2… f5!? to be the most important. Grandmasters and world champions of course see it quite differently: Magnus Carlsen, who plays 1.e4 Nc6 in blitz and rapid chess games (among others against ex-world champion Anand), answers 2.Nf3 with d6. He will know why :-), and as soon as I am stuck with 2… d5 and 2 … f5?!, I will take a closer look at this option.
1.e4 Nc6 2.Nf3 d5
The Scandinavian advance of the d-pawn is logical and leads to a side variation of the Scandinavian Defence, where White plays Nf3 (instead of Nc3) in the third move. However, in this side-line variation, White continues with Nf6 or Bg4 far more often than with Nc6. Well, in the TDKS you don’t have to worry about this; the dark knight has already excluded this option in the first move.
The black plan is relatively simple: Bg4, if possible e5 (otherwise e6), 0-0-0 and pressure against the pawn/point d4. This is usually easy to achieve when white develops “calmly”; only early more aggressive white play poses a challenge to the TDKS player.
1.e4 Nc6 2.Nf3 f5?!
A personal reminiscence may be allowed. In the 80s/90s, when I still had enough time to play chess intensively over the board and in the club, I regularly played 1… Nc6 against 1.e4 (against 1.d4 the thought honestly didn’t occur to me then, I preferred Dutch). Admittedly, my preference for 1.e4 Nc6 was due more to youthful enthusiasm for unusual ideas than to opening theory analyses, and the facial expressions of my (mostly older) opponents, which ranged from confused to shocked, were a positive fun factor in themselves. And so I naturally propagated the advantages of the Nimzowitsch Defence to my club friends, but without being able to convince them (no one else in my club included Nc6 in their repertoire). Last but not least I had to put up with the – seemingly justified – remark that after 2.Nf3 everything was only a transposition of moves. And indeed, I played against 2.Nf3 e5 for a long time myself, only to be able to become a bit exotic again with Hungarian (Be7 instead of Bc5) when it ran out in Italian, which was the predominant opening in my playing class at that time.
And so on a carnival Friday (for non-Rhinelanders: that’s the day between Fat Thursday and the long carnival weekend) the above-mentioned discussion took place again in the sparsely visited club room. And without any alcohol influence (I promise) I played, provoked by my smirking opponent, in a Blitz game spontaneously after 2.Nf3 f5?! with the words “No transposition of mives!” No idea anymore whether my preference for Dutch (against 1.d4) had given me the spontaneous idea. In any case, in several entertaining Blitz games that evening it turned out that 2… f5?! looked “stupid” but could by no means be refuted out of hand. The ” Carnival Gambit” was born.
Years later I learned that a child can obviously have many parents. 1.e4 Nc6 2. Nf3 f5 is of course not known in the opening theory as the Carnival Gambit, but as the Colorado Defence (the first game is said to have been played in Colorado in 1978). However, since it is not unusual to call the same opening in German by different names (Spanish Opening vs. Ruy Lopez), I will stick to the term Carnival Gambit here.
Since then, I have played the Carnival Gambit both online and offline in all kinds of variations, from Bullet to correspondence chess! The practical success has always exceeded the theoretical concerns. Yes, the Carnival Gambit is certainly either interesting (!?) or dubious (?!), probably somewhere in between, but !?! I don’t want to invent it as an additional annotation. At least it is so interesting that GM Kritz discussed it in a Chessbase video about some years ago.
The most fun is surely the variation in the game over the board. In the best case you will meet an (let’s stay in the cliché: older) opponent, who tries to play a Ruy Lopez game with White, maybe even the exchange variation. After 1… Nc6, he gets big eyes, and after a quarter of an hour of reflection, he decides against the “refutation” 2.d4 and sets himself with 2.Nf3 to 2. … e5 and continues as planned. And without hesitation you “slam” 2… f5 onto the board. Just imagine the expression on his face :-).
In the last years I have (in the online game, there is not enough free time for over the board anymore) increasingly turned to 2… d5 (here too with good results). My recommendation for the amateur player: first start with the more serious 2… d5, and then add the Carnival Gambit to your repertoire; either to surprise opponents, or to prevent others – who know your repertoire – from playing 2.Sf3.