Nimzo-Indian Defense: Sämisch Variation, Romanovsky Variation

The opening move of 1.d4 serves two purposes: controlling the center pawn and preparing to develop the pieces. This move allows White to control more space on the board compared to other initial pawn moves. It also allows the Queen's pawn to protect the c4 square, which is a crucial square in the Nimzo-Indian Defense. By controlling the center, White has more options to expand and develop their pieces, giving them an advantage in the game.

Black's move Nf6 is a common response to 1.d4 as it also has the duel purpose of controlling the center and preparing to develop the pieces. By centralizing the Knight, Black is putting pressure on White's d4 pawn. This move also prepares Black to castle their King and place a Knight on d5 square, which can be strong outpost in some variations. In sum, Nf6 is a flexible move that allows Black to react to White's future moves accordingly.

White's move c4 is a typical response to Black's Nf6. This move further controls the center and allows White to bring their Queen's Knight out to c3. Additionally, c4 prepares for a potential pawn exchange on d5, gaining additional control of the center. This move also opens up a line for White's Queen Bishop, which can be developed to attack Black's weakened pawns on c7 or f7. In sum, c4 is a strong move for White and provides many opportunities for strategic development in the opening.

In the Nimzo-Indian Defense: Sämisch Variation, Romanovsky Variation, Black's move e6 serves multiple purposes. It further reinforces Black's control over the d5 square and sets up a potential pawn structure with pawns on d5 and e6. This structure can provide a solid foundation for Black's pieces and limit White's potential pawn breaks in the center. Moreover, e6 prepares to develop the dark-squared Bishop, which can be placed on either d6 or b4. The move e6 also prevents White's pawn on f3 from attacking Black's Knight on g4.

White's move Nc3 in response to Black's e6 opens up a line for White's Queen which can develop to attack Black's a5 Bishop or support the d4 pawn. This move also prepares for the pawn break d4-d5, if Black doesn't prevent it. Additionally, the Knight on c3 supports White's control over the center and provides an alternative attack on Black's Knight on f6. In sum, Nc3 is a flexible move that can allow for various pawn, Knight and Bishop developments for White, depending on Black's response.

Black's move Bb4 in response to Nc3 pins the Knight to the Queen and threatens to capture it with the Bishop. This move also puts pressure on White's central control by attacking the pawn on d4. By developing this bishop along the long diagonal, Black controls key central squares d5 and e4 and prepares for eventual castling. Bb4 also allows Black to exchange their Bishop for White's Knight on c3, which may weaken White’s pawn structure. In sum, Bb4 puts White under pressure to respond accurately and makes it difficult for White to execute traditional plans.

In the Nimzo-Indian Defense: Sämisch Variation, Romanovsky Variation, White's move f3 is a typical move designed to defend the Knight on c3. This move helps to prepare White's Kingside for castling by reinforcing the g2-square and preventing any potential check using Black's Light-squared Bishop. Additionally, f3 controls the Knight on e4 square, which can be an annoyance for White. This move also supports the pawn push e4 to gain control over the center. However, f3 has a downside as well, as it weakens White’s control over the e4 square and may lead to a potential attack against White’s Kingside pawn structure.

Black's move d5 in response to f3 advances the pawn to challenge White's control of the center, further targeting the d4 pawn. This move also frees the Bishop on c8 and allows Black to develop it to d7 or b7, pointing at White's weakened pawn on c4. Moreover, d5 gives an opportunity for the Queen's Knight to jump to c5 square in the future and attack White's central pawns. However, playing d5 too early can also open up lines for White's pieces and weaken Black's pawn structure in the center. In sum, d5 is a solid move that requires careful consideration of the position.

In response to Black's move d5, White's move a3 is a prophylactic move, which prevents Black's Knight from going to b4 square and attacking White's Bishop on c1. Essentially, the move a3 breaks the pin on the Knight and prevents potential tactics that can cause trouble for White. Additionally, a3 gains space on the Queen side and serves as a tempi to improve White's position in the meantime. However, such a move weakens White's Queenside pawn structure and can be turned into a potential target for Black to attack. In sum, a3 is a solid move for White and requires careful calculation of its implications in the overall position.

In the Nimzo-Indian Defense: Sämisch Variation, Romanovsky Variation, Black's move Bxc3+ takes advantage of the exposed position of White's pawn on c4. This move is a tactical shot to weaken White's central pawn structure, opening up the long diagonal for the dark-squared Bishop and forcing White to recapture with the b-pawn, which could also be a potential weakness. Additionally, after the exchange, Black's Knight can be placed on b6 square and attack the pawn on c4. However, playing Bxc3+ too early can also lead to vulnerability for Black’s King and disrupt Black's development. In sum, Bxc3+ is a promising move that requires careful judgement of the position.

White's move bxc3, in response to Black's Bxc3+, recaptures Black's Bishop with the pawn while opening up the b-file for White's Queen Rook. Additionally, White's pawn doubling on the c-file can limit Black's control over this area and potentially create an isolated pawn on d5. By capturing with the b-pawn, White also maintains their pawn structure and protects the pawn on d4, which can be an important central control point. However, bxc3 also has a downside, as it weakens White's b2 square and the Knight can jump there in the future and create additional weaknesses for White. In sum, bxc3 is a solid move that requires careful judgment of the position and a precise calculation of its implications.

In response to White's move bxc3, Black's move c5 challenges White's central pawn structure while gaining additional space on the Queen-side. This move also supports the Knight's jump to the center, controlling the key d4 and e4 squares. Additionally, c5 gains control over the d4 square, providing additional flexibility and opportunities for future moves. However, playing c5 too early can also lead to the loss of the pawn and the weakening of Black's pawn structure. In sum, c5 is a typical move in this type of position and requires careful assessment of its consequences.

In the Nimzo-Indian Defense: Sämisch Variation, Romanovsky Variation, White's move cxd5, in response to Black's c5, opens up the center and creates an isolated pawn on d5 for Black. This move also allows White to potentially control more space on the board, which can be leveraged to launch an attack. By capturing with a pawn instead of a piece, White preserves their pawn structure and gains a passed pawn on d5 square. However, exchanging pawns also opens lines for Black's pieces and can be used to generate counter-play. In sum, cxd5 is a dynamic move that requires accurate evaluation and tactical awareness.

In response to White's move cxd5, Black's move Nxd5 exchanges a central pawn for White's Knight, getting rid of a potential attacker of Black's central pawns. After the exchange, Black's Queen Knight is centralized and exerts pressure on White's pawn on c3, which is unprotected and can potentially be captured. This move also opens up the path for Black's dark-squared Bishop, targeting a potentially weakened pawn structure on the Queenside. However, Nxd5 also gives White an isolated pawn on d5, providing fresh opportunities to exploit Black's isolated pawns. In sum, Nxd5 is a dynamic move that requires careful assessment and a clear understanding of the resulting position.

White's move dxc5, in response to Black's Nxd5, opens up the diagonal for White's light-squared Bishop and gains the advantage of controlling more central squares. This move also attacks Black's undefended Knight on d5 and forces Black to recapture with their pawn, potentially creating additional weaknesses on the Queenside. By capturing the pawn with the Queen's pawn instead of Knight, White preserves their Knight's position on c3, limiting Black's control over the center. However, dxc5 also weakens White's b2-square and can create a potential target for Black. In sum, dxc5 is a dynamic move that requires careful calculation of the position and an understanding of the resulting imbalances.

In the Nimzo-Indian Defense: Sämisch Variation, Romanovsky Variation, Black's move f5, in response to White's dxc5, attacks White's Knight on c3 and gains additional space on the Kingside. This move also breaks up White's central pawn structure, which can be weak and isolated after the exchange of pawns. By playing f5, Black also prepares to bring their Knight to f6 square, controlling crucial central squares. However, f5 also creates a potential weakness around Black's Kingside, that can be exploited by White's pieces. Additionally, playing f5 too early can release White's central pawn tension and provide additional attacking opportunities for the opponent. In sum, f5 is a dynamic move that requires careful assessment of the position and a clear understanding of the pros and cons.