The Kennedy Advance Variation
One may justly wonder what Black can possibly gain by tempting White's d-pawn to d5, freely giving a space advantage. But in fact the King's Indian Defence has been doing this for 80+ years (ever since it's invention) and it is recognized as a sound, dynamic defence. So why not the Nimzovich?.
1) Pieces-only Development
A natural plan consists of the piece formation Be7, Nf6, and Ng6, aiming to develop quickly and reduce opportunities for White to grow his advantage. All three pieces have prophalytic duties.
- Be7 protects the d6 pawn, and also stops c4-c5.
- Nf6 discourages Be3, as otherwise Black uses Ng4 followed by f5.
- Ng6 means that a knight is always ready to jump to f4
The downside is that Black blocks his own pawns, and thus cannot unleash the storm against White's kingside.
2) The King's Indian Defence
After moves like ...g6 and ...Bg7, Black has transposed into the full King's Indian Defence. The KID was the absolute favorite of top GM's for many years, but they all quitted after White discovered the Bayonet Attack variation. Well - the KID is still alive. The nice thing is that there's a lot of study material available.
3) Grindian Variation
I call this the Grindian because it combines the King's Indian idea of a kingside pawnstorm with the Grob Attack move, g5. Unlike a traditional KID which uses g6 and Bg7, the Grindian uses the moves h6, g5, and Bg7. It's therefore more ambitious and yet flavorfully distinct from the KID.
- Black gains more space compared to the g6 setup.
- Black is able to play Ng6.
- The f7-f5 pawnbreak is compromised due to Black's inability to recapture with a pawn. Hence White might gain a valuable knight outpost on e4.
- White may challenge the g-pawn with h4, or even prevent it from getting to g5 by playing h4 first.
- White may run away by castling queenside. Still, space is space.
4) Bb5+ Variation
Honestly I don't think this check does very much for White. After blocking with c6 Black emerges with the central pawn majority and a Sicilian-ish position. White retains a lead in development and has a target on d6, but I still like Black.
5) f4 Gambit
An important sideline for Black to remember. White should not be allowed to make such a strong strategic advance unmolested. In fact - if Black plays correctly, White can't get anything out of this - because the move f2-f4 actually weakens the White king.
6) Bishop outside the pawn chain
Mostly I have given Black the move d6 in response to Nf3. The move d6 of course locks the bishop behind Black's pawn chain. But if Black wanted then he could play Bc5 before d6, but personally this is not to my taste. The following analysis gives White a strong game but no clear win:
Master Games
1) Pieces-only Development
2) King's Indian Defence
3) Tango
4) White plays h4
The Maverick's Right-Sided Nimzovich Defence
To be distinguished from the "left-sided" Nimzovich Defence. This is a thread devoted to the line 1. e4 Nc6!? 2. d4 e5. Black's pawn thrust, 2...e5, comes from the right side of the chessboard.
The character of the Nimzovich is "hypermodern" - leading with pieces instead of pawns. Unlike other "hypermoderns", though, the Nimzovich Defence has never caught on especially at the Master level. Simply put things happen for a reason:
White's second move, d4, sets up the "classical center" which Black will do well to immediately challenge with either ...e5 (right-sided) or ...d5 (left-sided). Personally, I don't really believe in the left-sided version because after 3. e5 Bf5 Black just has an inferior version of either the Caro-Kahn Defence or French Defence. As a 1...e6 specialist myself I could just go for the real thing.
Strategy
The c6 knight is used positionally not as development, but rather to launch a dark-square campaign. It is a positional bait to tempt the advances d4 and d5, so that White will permanently weaken the dark squares on the long diagonal, especially the e5 square. The natural follow-up is to then place a bishop on g7. Alternatively the bishop might go to b4 or c5.
Black also often goes out of his way to provoke pawn advances (actually this is kind of risky). The idea is to infiltrate through squares weakened by such advances; as the pawns are normally quite stable themselves, Black's only chance to get at them would be in an endgame which is still far off.
Basic Positions
1) Kennedy Advance Variation (1. e4 Nc6 2. d4 e5 3. d5 Nce7)
The Advance Variation gains space for White and temporarily cramps the Black pieces on the kingside. Thankfully, it also closes the center, which buys Black enough time to un-cramp.
The play and structure resembles a King's Indian Defence, or, if Black plays c5, a Benoni. However, both players have more flexibility because the pieces and pawns are not yet committed. Therefore one can play this variation both safely, or in the riskiest manner possible.
2) Kennedy Exchange Variation (1. e4 Nc6 2. d4 e5 3. dxe5 Nxe5 4. Nf3)
The Exchange Variation is a more direct way to play for an advantage - White simply makes the knight move, and hopes to capitalize on tempo. Conversely, Black argues that he gained the e-file, and Black's d-pawn is safer than White's e-pawn. It is quite logical - White will often go all-in with f4, g4, h4, whilst Black simply plays d6 and waits for the storm to pass.
The effect is that Black, playing with pieces, goes hunting for holes, outposts, and weak diagonals, hopefully setting up a blockade - while White, playing with pawns, simply tries to bury his opponent. Clearly the Black game is more difficult, but once mastered it will be White who will struggle to get an advantage. Black by the way has to be a "master of defence" to survive this dangerous variation.
3) Kennedy Grand Prix (1. e4 Nc6 2. d4 e5 3. dxe5 Nxe5 4. f4 Ng6)
With the move f4 White gains a big space advantage by setting up the "Grand Prix" center. It becomes immediately obvious that he cannot wait to attack - a hastiness which weakens the dark squares and exposes both pawns to counterattack. Black should soon play 5...Bb4+ to provoke c3 and then 6. Bc5 to prevent Kingside castling.
Compared to the Nf3 variation, Black ironically defends his position more easily. Many themes of the Exchange Variation echo in the Prix, except that Black doesn't need to work for square control - White has already done the job for him.
4) "Robust" Variation (1. e4 Nc6 2. Nf3 g6)
No repertoire of the Nimzovich Defence is complete without an answer to Nf3. Although White doesn't build a pawn center, he is inviting 2...e5, transposing into the Ruy Lopez which is actually quite good for Black. But 2...g6 is a good move transposing into the Robatsch Defence.
Black only needs to be concerned about one extra possibility - White's threat of d4 and d5, driving the knight away. In my opinion Black should try Nb8!?, negating development but claiming the long diagonal. The d-pawn can never move backwards from d5 to d4 to block the dark-squared bishop on g7 .
5) "Birdy" Variation (1. e4 Nc6 2. Bb5 Nd4)
This early Bb5 is easily negated by the "Bird Defence" to the Ruy Lopez, which characterized by the move Nd4. My concept is to play c5, unleashing the normally blocked c-pawn, and then transposing into an Alappin Sicilian after White's c3. It's good because the Alappin offers no more than a slight edge to White.
6) Scotch Game (1. e4 Nc6 2. d4 e5 3. Nf3 exd4)
Once condemned for "releasing the central tension", the Scotch is now fashionable again thanks to super-GMs such as Magnus Carlsen. But unlike the other setups White has no extra tempo and only minimally more space. Black should equalize quite easily and play simple replies against any gambits.
(I half-believe that to get any advantage at all White must drop a pawn, to which Black should politely refuse.)