Ruy Lopez: Bulgarian Variation

In the Ruy Lopez: Bulgarian Variation, White starts the game by playing e4. This move initiates an aggressive approach towards controlling the center of the board. By placing a pawn on e4, White aims to control the d5 and f5 squares, impeding Black's central pawn advances. It also frees the bishop on f1, creating a path for development and preparing the way for future castling. e4 is considered a strong and common opening move because it immediately puts pressure on Black's position and sets the tone for the game.

Black's response to e4 is frequently e5 in chess. This move seeks control over the central squares and challenges White's pawn formation. By advancing the pawn to e5, Black prepares to develop the knight and bishop to active positions. Additionally, it creates a path to control the d4 and f4 squares, making it difficult for White to establish a central pawn advance. The e5 move can also lead to a sharp and tactical game, introducing opportunities for counterattacks and leading to highly dynamic play.

In response to Black's e5, White plays the move Nf3 which represents a classical opening for the Knight. It controls the important central square on d4, while also preparing to castle kingside. The knight on f3 also enables White to support the central pawn with d2-d4, which may lead to a pawn break in the center and a stronger pawn structure. Additionally, the Nf3 move gives White flexibility in their development, as the knight can later recapture on e5 or move to other squares depending on how the game develops. In sum, Nf3 is a solid and principled move that seeks to control the center and establish a firm position early on in the game.

In the Ruy Lopez: Bulgarian Variation, after White plays Nf3, Black typically responds with Nc6. This move develops the knight towards the center and prepares for future moves like d7-d6 and Bc8-b7. The knight on c6 also attacks the d4 square, disrupting White's central pawn control and forcing White to consider pawn pushes like c2-c3 or d2-d3 to reinforce their position. Moreover, Nc6 supports the e5 pawn, enabling Black to potentially push it forward to e4 to gain more space control. This move is a common and natural response in the Ruy Lopez, allowing for solid development and the opportunity to contest the center.

In response to Black's Nc6, White commonly plays Bb5 in the Ruy Lopez opening. This move pins the knight and puts pressure on the e5 pawn, which is not protected by any other pawns. Moreover, the bishop on b5 can threaten Black's knight on c6, which may need to move or be exchanged. Bb5 also opens up the possibility of castling queenside, allowing White to complete their development and put their king in a safer position. In sum, Bb5 is a tempo-gaining move that seeks to increase White's control in the center and put early pressure on Black's position.

In response to White's Bb5, Black can play a5, which is known as the Ruy Lopez: Berlin Defense. This move stops White's pawn from advancing to b4 and forces the bishop to retreat to a4 or c4. It also prevents the possibility of White playing Nb5 in the future, attacking the c7 square. Additionally, a5 prepares a queenside expansion with b7-b5, gaining space and pressuring White's pawn structure. However, a5 also weakens the b5 square, which can be targeted by White's pieces in the future. In sum, a5 is a solid move that seeks to contain White's pressure and establish counterplay on the queenside.