Polish opening starts with 1.b4. White ignores the center and gives black an opportunity to choose the structure. White’s idea is to fianchetto the bishop with Bb2. Since move 1.b4 doesn’t put pressure in the center, it allows black many opportunities to play.
Black plays 1…e5
With 1…e5, black attacks the b4 pawn. White doesn’t have to defend it immediately. White can play 2.Bb2, attacking the e5 pawn.
Black can play 2…f6 and renew the attack on b4 pawn. Black can also play 2…d6 and establish a strong center on e5.
The main move is to capture with 2…Bxb4. After 3.Bxe5, the game can go 3…Nf6 4.Nf3 Nc6 5.Bb2 d5 6.e3 0-0 and we reach the position below.
White has 2 center pawns against black’s one. That gives white a possibility to play for a strong center. On the other hand, black has a lead in development. White can play 7.Be2 and 0-0 to complete his development or try 7.c4 with a direct attack on the center. We have an interesting positional battle ahead.
Note that 2…Nc6 is black because white has 3.b5
After 3…Nb4 4.e3 Ne6 5.Bxe5 white wins a pawn. So 2…Nc6 is not recommended for black.
Black plays 1…d5
After 1.b4 d5 2.Bb2 Nf6 3.e3 Bf5 4.Nf3 e6 5.a3 we have a position below.
Black has established a strong d5 square on the center while white attempts to control e5 square. The position is similar to the queen’s pawn opening with the difference that white has advanced queenside pawns.
Black can continue with Bd6-0-0-Nbd7 and c5 with a good game. Since white wasted a move on b4 and then a3, black has no problems in the opening.
Black plays 2…Qd6
An interesting move for black is to play 2…Qd6. It is a very good move because black takes advantage of the weak b4 pawn and at the same time takes control of the e5 square.
White can’t play 2.b5 to defend the pawn here because of Qb4! And black wins a pawn.
So white has to play 3.a3 giving black a good control of the center. The game can continue 3…e5 4.Nf3 f6 5.e3 Be6 6.d4 e4 7.Nd2
Black has a space advantage and white will try to put pressure on the center with c4. This set-up is similar to French defense but with the opposite colours. Notice how wasting one move in the opening can allow the opponent to take space advantage.
Black plays 1…a5
Finally, black can play 1…a5, going with the flow of white’s first move. Black challenges the b pawn and forces it to move forward before starting to develop the center. After 2.b5 Nf6 the standard developing moves continue.
Conclusion
Polish opening is a good way to experiment with your positional playing skills. White essentially gives black the first move by playing 1.b4. It can be a good way to surprise opponents at a beginner level and make him think right from the 1st move.
However, it is not recommended choice for serious game because it gives away the 1st move advantage for white. Black has nothing to fear and can simply develop in the center, choosing a set-up that he is comfortable with.