Demo # 5

1. ...  f6

The chess engine prefers to create pawn tension, just like the previous example.

The black pawns on f6 and g6 control important squares, at no point does the chess engine even consider the move f7-f5.

2. d4  Kf7

The chess engine prefers to play exactly the same moves to maintain pawn tension  

This blocking rule is very old, I have been using it for years.

I always watch for it closely when playing over grandmaster games and checking things with an engine.

I was very surprised, back in the early days, to discover that engines and grandmasters in the main prefer to single step to create pawn tension in the position.

There are exceptions to that general rule of thumb of course, mainly:

When there is a piece, mainly knights, on a strong outpost then a double step is sometimes played to kick it away and force an immediate decision to either capture by en passant or to move the piece.

When the engine wants to radically change the pawn structure to either close the position or open a file and diagonal then a double step is sometimes played.

But now it is a lot more simple, there is no radical change in pawn structures that require an immediate forced decision.

The blocking rule only applies to double steps on the game board.

Pawn drops are not affected by the rule as shown in the example below.

1. d2

This white pawn drop is legal.

The black pawn can not capture cxd1 like en passant.

Double drops are also not affected by the rule as shown in the example below.

1. Nd2

This is a legal drop.

The example is a bit silly because the double drop now allows cxd2 losing the knight.

It is however a legal move so it must be shown, the blocking rule does not block double drops.

I have never liked the en passant rule in chess.

I remember always feeling uncomfortable at the board when a double step could be played allowing capture in passing.

Double steps do speed things up across the board but for me they cause friction when two opposing pawns have drawn close enough to each other.

The blocking rule simply slows things down to single steps in a local area of the board so that there are no abrupt forced changes in pawn structures.

The en passant rule is a problem in programming.

This was the reason why I started thinking about a new rule years ago.

The en passant rule creeps into code everywhere because it affects game state:

Zobrist hashing, FEN strings, Repetition of position rule and probably more things but I am too lazy to think about it again because it does not affect my game and is no longer my problem.

I was never comfortable with en passant at the board but changed the rule because of programming?

I then checked it for years when playing over grandmaster games, something that I still do in positions where opposing pawns have drawn close together.

The strange thing is that this slight change taught me a lot about pawn tension and pawn structures across the entire game board.

The best board to use is a nice wooden board that has a frame that is at least as wide as a square on the game board.

If the board does not have a wide enough frame for the side boards then just use the playing surface for the side boards.

There are 2 game types: Symmetrical and Asymmetrical.

With the symmetrical setup the black pawns are done in the same way as white from files A to H.

Note that in this simple symmetrical example the black units and pawn structures are located on the same flank as white but they are on opposite coloured squares.